This PDF file contains the front matter associated with SPIE Proceedings Volume 7125, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

Recently, in the magnetic recording, head assisted magnetic recording (HAMR) and patterned media (PM) technology have been considered as strong candidates to achieve the high recording density beyond the super-paramagnetic limit. Using E-beam recording (EBR) and UV nano-imprinting, the PM with nano-scale pitches and tracks is fabricated effectively and delicately. And the optical throughput of the HARM system is improved by optimizing the grating and the media geometry. In the optical storage, next generation technologies are the near filed recording (NFR) and the holographic recording. The modified NFR gap servo mechanism is developed and clearance of 30nm is uniformly maintained. In addition, the anti-shock servo algorithm resists against the external shock of over 2G@10ms. The advanced holographic system compensates the errors from disturbance by finding the max intensity angle with back propagation algorithm for angle direction and shifting the reference beam with glass plate controlled by a servo motor for fractal direction.

Multilevel storage is the easiest two-dimensional storage technology. On the basis of recording and read-out optical system of Digital Versatile Disc (DVD), by the method of multilevel run-length coding, the storage capacity can be increased by 60 percent of DVD9's, reaching 14 Giga Bytes. In order to meet the requirement of a 10^-4 raw Bit Error Rate (BER) of data readout, this paper presents a method of multilevel run-length coding with changeable level numbers. This method can take advantage of run-length redundancy to the utmost and reduce Inter-Symbol Interference (ISI) caused by multilevel run-length. Multilevel run-length coding uses the method of two steps modulation. This paper introduces a coding method of DK (1, 9) and R=1 code rate. Realized by Pulse Width Modulation, multilevel run-length modulation coding with changeable level has good symmetry. Its readout characteristics are the same as that of DVD with normal run-length modulation, therefore the servo control system needn't be changed. Also the signal can be recognized in two aspects respectively, run-length and level. In the sample disc, average raw BER in the two aspects is less than 10^-3. Multilevel run-length modulation coding could be applied in various systems of run-length modulation coding. On the basis of the structure and characteristics of the primitive system, the comprehensive efficiency of coding could be increased by 33 to 50 percent.

The PMMA material doped with high content of PQ is fabricated in our Lab. Dynamic range is studied to be 2.5mm^-1 by peristrophic multiplexing. In Angular multiplexing based on rotating material, 100 frames of gray image are recorded in a 1mm thick sample and the reproduced images have a good quality. The storage capacity is calculated to be 3.1× 10⁹ bits/cm³, which implies that our PQ/PMMA material is suitable for volume holographic storage. The intensity of grating increases with time and the shift of sensitivity angle, which is about 0.1375 deg for each multiplexing image in reproduced process, are also found. We give a qualitative analysis from the aspect of dark reaction of sample.

We report experimental results of forming marks about 100~150nm in diameter on chalcogenide alloy thin films with a semiconductor laser of wavelength λ=650nm and a focusing lens of 0.65 numerical aperture (NA). The fact that the mark sizes are obviously smaller than the diffraction limit (The mark diameters are about 1/10 of the focused light spot) is explainable by analyzing the nonlinear absorption inside the thin film that is caused by the focused light spot of a Gaussian intensity distribution.

Nowadays, OMNERC research group is going to advance the capacity to 15GB by reducing the 3T pit length and increasing the level of long pit based on the signal waveform modulation (SWM) ML recording technology. In order to prove this method is realizable, this paper proposes the restriction points of consideration to reduce the minimum pit length which influence the basic specification design of multi-level disk and the difficulty of the following signal processing. Firstly the restriction of optical pick-up resolution is considered. Secondly, the restriction caused by read-out channel is discussed in the paper. At the same time as write strategy has its limit based on the previous research, this paper finally discuss the influence caused by minimize shortest pit length for level design of long length pit.

Our team have proposed and implemented a new type of multi-level DVD, which features in using the waveform to differentiate levels. Servo accuracy is an important issue for an optical disk system, since it can directly influence the quality of readout signal. This paper analyses the influence of servo error on the readout signal for our multi-level DVD using numerical simulation. A readout model is established, where focus error (FE) and tracking error (TE) is introduced. A new parameter, waveform deviation, is proposed to quantitatively evaluate the influence. Simulation results show that the influences of TE/FE on readout signal are similar. Each of them will shrink the dynamic range of readout signal. When TE/FE exceeds a threshold, the waveform deviation will increase sharply.

The Radio Frequency (RF) signal of the Multi-Level Run-Length-Limited (ML-RLL) read-only disc is different from that of DVD, so the readout system of the ML-RLL read-only disc is built specially. The readout system of the ML-RLL read-only disc can realize servo control, RF signal readout and so on. The readout system consists of Digital Versatile Disc (DVD) traverse, analog front-end and digital processing part. Analog front-end can realize front-end amplification of the output signal of the optical pick-up and power drive of mechanism. Digital processing part mainly consists of digital circuits, which functions are the servo controlling, demodulation and decoding of RF signal, general control and so on. The whole system is implemented on two Field Programmable Gate Array (FPGA) chips and the experimental results show a good performance. We tested the important signals, and experimental results are also given to verify the performance of this development platform, which meets the controlling and detecting requirements to multi-level read-only disc completely. The Bit Error Rate (SER) can achieve below 10^-4.

A new symmetrical photochromic diarylethene, 1,2-bis[2-methyl-5-(3-methoxylphenyl)-3-thienyl]perfluorocyclopentene (1a), was synthesized, and its photochromic properties were investigated. The compound exhibited good photochromism both in solution and in PMMA film with alternating irradiation by UV/VIS light, and the maxima absorption of its closed-ring isomer 1b are 582 and 599 nm, respectively. Using diarylethene 1b/PMMA film as recording medium and a He-Ne laser (633 nm) for recording and readout, four types of polarization and angular multiplexing holographic optical recording were performed perfectly. For different types of polarization recording including parallel linear polarization recording, parallel circular polarization recording, orthogonal linear polarization recording and orthogonal circular polarization recording,have been accomplished successfully. The results demonstrated that the orthogonal circular polarization recording is the best method for polarization holographic optical recording when this compound was used as recording material. With angular multiplexing recording technology, two high contrast holograms were recorded in the same place on the film with the dimension of 0.78 μm².

In this paper, a new method of 3-D data cube based on virtual holographic storage is presented. Firstly, the data information is encoded in the form of 3-D data cube with a certain algorithm, in which the interval along coordinates between every data is d. Using the plane-scanning method, the 3-D cube can be described as a assembly of slices which are parallel planes along the coordinates at an interval of d. The dot on the slice represents a bit. The bright one means "1", while the dark one means "0". Secondly, a hologram of the 3-D cube is obtained by computer with virtual optics technology. All the information of a 3-D cube can be described by a 2-D hologram. At last, the hologram is inputted in the SLM, and recorded in the recording material by intersecting two coherent laser beams. When the 3-D data is exported, a reference light illuminates the hologram, and a CCD is used to get the object image which is a hologram of the 3-D data. Then the 3-D data is computed with virtual optical technology. Compared with 2-D data page storage, the 3-D data cube storage has outstanding performance in larger capacity of data storage and higher security of data.

A symmetrical photochromic diarylethene, 1,2-bis[5-(3,5-difluorophenyl)-2-methyl-3-thienyl]-3,3,4,4,5,5- hexafluorocyclopent- 1-ene (1a), was synthesized, and its photochromic and fluorescent properties were also investigated. The results showed that this compound exhibited reversible photochromism, changing from colorless to blue after irradiation with UV light both in solution and in PMMA amorphous film. In hexane solution, the open-ring isomer of the diarylethene 1 exhibited relatively strong fluorescence at 350 nm when excited at 280 nm. The fluorescence intensity decreased along with the photochromism upon irradiation with 297 nm light and its closed-ring isomer showed almost no fluorescence. Using diarylethene 1 as recording medium, polarization holographic optical recording was carried out successfully.

The dynamic theoretical model of photochemical and hologram formation in holographic photopolymer is established, and the dynamic development process of holographic storage in the photopolymer is discussed with the model. A holographic photopolymer sensitized by erythrosine B is prepared, which is composed of acrylamide as monomer, ployvinylalcohol as binder, triethanolamine as initiator. The influence of the exposure intensity on holographic storage characteristics is analyzed. The experimental data of transmittance and diffraction efficiency of the fabricated photopolymer with different exposure intensities are obtained. By means of fitting the experimental data of transmittance and diffraction efficiency as a function of time with five exposure intensities at a wavelength of 514nm, the variation of photochemistry and photopolymerization diffusion dynamic parameters such as the molar-absorption coefficient ε, quantum yield Φ, photobleaching coefficient k_p, polymerization rate k₀ and diffusion time constant τ_D is presented. The research results show that as the exposure intensity increases, so do also ε, k_p and k₀, but Φ becomes smaller. And τ_D has no obvious changes except the sample is overexposed. This material has the characteristics of longer diffusion times for the monomer to travel from the unexposed to the exposed zones than that in the case of other polymeric materials.

Multi-level run-length limited (ML-RLL) recording technology can increase the capacity of the read-only disc without changing the optical and mechanical units. The characteristic of the push-pull signal of the multi-level run-length limited read-only disc is analyzed and compared with that of the conventional DVD read-only disc. Experimental results show the effect of the variation of pit depth is more than other parameters and the peak-to-peak amplitude of the push-pull signal in the ML-RLL read-only disc is about 2.9 times of that in the DVD read-only disc while the variance is nearly 3.2 times. The push-pull method in the ML-RLL read-only disc is more sensitive than that in the conventional DVD read-only disc.

In this paper, a new method of 3D data information encryption with virtual holography is proposed. The data information is encoded in the form of 3-D data cubes. A cube can be described as an assembly of slices which are parallel planes along the coordinates at an interval of d. The dot on the slices of the 3-D data cube represents a bit, and the bright one means "1", while the dark one means "0". The hologram of the 3-D cube is generated in computer with virtual holography, and the hologram can be transformed into a secondary hologram with virtual holography technique again. Thus the 3-D data cube can be encrypted in the form of the secondary hologram, in which the parameters are used as the keys, such as the wavelength of light, the propagation distance of wave, the geometrical parameters of the data cube and so on. Only all of the parameters keys are provided correctly, the data information can be retrieved entirely. Numerical experiments are performed to illustrate the ability to encrypt the 3-D data information with virtual holograph technique. The computer simulation results show, that the data information can obtain higher security and certain robustness with this method.

The angular selectivity was analyzed theoretically and numerically in the holographic storage system with the spherical wave as reference beam. The results show that angular selectivity relates with the crystal thickness and independent on z0. Experiments performed with Zn:Fe:LiNbO₃ crystals also proved the prediction.

This paper presented an experimental study of holographic scattering caused by noise gratings recorded in the PQ-PMMA photopolymers. Dependence of the thickness and temperature on the holographic scattering losses was evaluated. It is found that the scattering losses increased as the thickness and temperature. According to the relationship between the polymerization rate and exposure, the optimal material parameters thickness 2mm and the temperature 20-30°C were obtained for avoiding the buildup of strong noise gratings.

In this thesis, two kinds of photopolymer films sensitized by azure I and azure II respectively are fabricated and their important holographic characteristics including the sensitive spectral range of films, transmittance, diffraction efficiency (DE), the thickness of photopolymer films and refractive index modulation are compared. It can be found that the photopolymer film sensitized by azure II(sample 2) has more obvious advantages than the photopolymer film sensitized by azure I (sample 1)on the holographic characteristics from the absorption intensity and the optimum concentration of dye and the inner uniformity of sample to the photochemical reaction velocity and the optimum medium thickness. On the contrary, sample 1 has higher maximum diffraction efficiency and refractive index modulation than sample 2.

Disc scratches, dusts and noise corruption et al. will cause data sequence errors including random errors and burst errors. With the recording density of multilevel (ML) optical storage system increasing, the same length of scratches on the surface of optical disc will bring more burst errors in ML DVD than conventional optical recording systems, e.g., digital versatile disc (DVD) and compact disc (CD). A new interleaving scheme based on Reed-Solomon code (RS) is proposed to solve this problem. In DVD system, the burden of the Parity of Outer-code (PO) is huge, while the Parity of Innercode (PI) has more correcting ability than needed. The new interleaving algorithm adjusts the structure of data frame and block and improves the interleaving depth of ECC block to reduce the burden of PO. The results of numerical simulations are presented to verify the performance of the new interleaving algorithm compared with RSPC. The new proposed scheme can correct maximum burst error length of the proposed code is 6912 bytes. Burst error correcting capacity of the proposed scheme is improved up to137.4% more than that of the RSPC.

Functional nano-heterostructures are of great interests in nano-photonics applications. A new strategy to obtain local nano-heterostucture formed by laser-induced eutectic transition is proposed in this paper. Numerical simulations demonstrate that periodic eutectic microstructures formed on binary eutectic alloy thin film during irradiation of a laser beam can result in a prominent near-field enhancement. Results can help to understand the microscopic mechanism of eutectic-binary-alloy-type super-RENS disk from a near-field optics view.

Super-resolution near-field structures (super-RENS) with antimony bismuth mask layer (Sb_1-xBi_x, X =0, 0.1, 0.2 and 0.9) were fabricated by magnetron sputtering. AgInSbTe and ZnS-SiO₂ were used as recording layer and dielectric layer respectively. Static recording tests with and without super-RENS were carried out using static recording tester whose laser wavelength is 406.7 and numerical aperture is 0.8. The recorded marks were observed by atomic force microscopy (AFM). The influences of Bi proportion in the films on the super-resolution recording properties were investigated.

It is distinctly indispensable to develop new high density storage of information because of its explosively increase. Super-resolution near-field structure (super-RENS), which breaks through the size limit of classical optics, is one of the most promising ways. In this paper, the newest highlighted progresses in researches of mechanism and material are discussed, and some problems in the future improvement are also analyzed.

In this work, we prepared high-coercivity SmCo₅ thin films with in-plane or out-of-plane anisotropy. Our research work focused on the induction of highly textured SmCo₅ thin films using suitable underlayers. A Cr underlayer was used for the fabrication of SmCo₅ with in-plane anisotropy. The nanocrystalline SmCo5 thin films with a (1120) texture exhibited high in-plane intrinsic coercivity up to 18.5 kOe. On the other hand, with a Cu underlayer, highly (0001) textured SmCo₅ thin films showed large perpendicular anisotropy and high coercivity up to 20 kOe. Our research work showed that a very thin seedlayer (4nm) of Ta can improve the crystallinity and texture of the (111) Cu underlayer. The high quality Cu underlayer can result in high magnetic performance of SmCo₅ thin films.

A self-ordered hexagonal array of nanopores has been fabricated by anodizing a thin film of Al on glass and subsequently the magnetic properties of TbFeCo on this templates were studied. We carried out anodic oxidation of a sputtered Al film at the anodic voltage in the range of 10-30 V and temperature in the range of 5-40 degrees C, and found that the density of the nanohole arrays increased with the decrease in anodization voltage and temperature. On the other hand, hole diameter decreased with the decrease in anodic voltage and temperature . Then TbFeCo was deposited onto this porous array by sputtering with a thickness of around 90 nm and subsequently was overcoated with 10 nm SiN for the protection from surface oxidation. The TbFeCo deposited on this porous layer shows complete perpendicular anisotropy and the AAO template can promot the growth of the microcolumnar structure in TbFeCo films. The coercivity increased with the decrease of hole diameter. The coercivity of the TbFeCo deposited on the porous array with a mean hole diameter of around 15 nm is 5.6 kOe and larger than that on bare glass, but the squareness ratio gets poorer than that on bare glass. Experience and simulation indicate that the magnetization reversal mode follows the Stoner-Wohlfarth .

The authors demonstrate microwave assisted switching process of Ni80Fe20 thin film element with micromagnetics. Effects of microwave amplitude and frequency on the magnetization reversal were focused. Numerical results showed that the coercivity of Ni₈₀Fe₂₀ thin film element can be reduced by the modification of the microwave field, and the most evident reduction of coercivity was found at resonance frequencies. Considerable Fluctuations of switching fields are found at the natural resonance frequencies and high microwave amplitudes, which can be explained by scattering of nucleation sites induced by the thermal effect of the microwave filed.

In this paper, we report the fabrication and characterization of two kinds of mediums for magnetically induced superresolution (MSR) and blue wavelength magneto-optical data storage. Both NdGdFeCo/TbFeCo and Pt₃Co/TbFeCo exchange coupled double layer structures show good MSR effect. At room temperature (RT), NdGdFeCo and Pt₃Co have in-plane magnetization, however, with temperature rising, they become out-of-plane magnetized and copy the bit information of TbFeCo because of strong exchange coupling. This suggests that both of the double layer films are good candidates for MSR/blue wavelength magneto-optical data storage.

The structured overlay networks based on DHT provide a decentralized, self-organizing substrate for building the large distributed systems such as file sharing and data storage. However, in most of these systems, many problems still remain to be solved regarding system scalability, network proximity and so on. In this paper, we present a novel routing protocol called PBHC. By combining hierarchical DHT algorithm with a data proximity mechanism PBHC minimizes the intracluster access traffic and boosts the local access ratio in heterogeneous networks environment. The simulation results show PBHC can significantly improve the routing performance and scalability of the P2P storage system.

Laser assisted magnetic recording properties were obtained by SiAg nonmagnetic mask layer combined near-field coupled super-resolution technique. The film structure was "Glass/SiN(30nm)/SiAg(20nm)/SiN(20nm)/TbFeCo(50nm)/SiN(10nm)". SiN and TbFeCo films were prepared by Radio frequency (RF) and Direct current (DC) magnetron sputtering respectively. The SiAg nonmagnetic mask layer was deposited by co-sputtering from a composite target. In the process of sputtering, the substrate negative DC bias voltage was kept at about 100V. Magnetic properties were obtained by vibrating sample magnetometer(VSM) and the magneto optical Kerr measurement. The magnetic recording was conducted by a home-made laser-assisted optic-magnetic hybrid recording setup, whose laser wavelength is 406.7nm and numerical aperture of converging lens is 0.80, respectively. The optical spot size is about 600nm. In the course of recording, the laser pulse was fixed at 100ns, and the magnetic field intensity was 300 Oe. The magnetic domains with a size of about 100nm were obtained, which is about 1/6 of the optical spot size. The analysis indicates that the SiAg nonmagnetic mask layer played a key role in reducing the magnetic domain size.

CoCrPt/Ti/C, CoCrPt/C/Ti and CoCrPt/C/CoCrPt/Ti thin film were prepared to study the effect of thin C layer insertion on the magnetic properties and microstructure of CoCrPt/Ti hybrid recording media. Surface roughness improvement and C atoms' diffusion to Ti underlayer contribute to optimized magnetic properties in CoCrPt/Ti/C films due to C seedlayer insertion. Very thin C intermediate layer gives rise to smaller magnetic grain size and improved perpendicular coercivity in annealed CoCrPt/C/Ti thin film while thicker C intermediate layer hinders the epitaxial growth relationship between Ti underlayer and Co-alloy magnetic layer. 3nm C intermediate layer in CoCrPt/C/CoCrPt/Ti thin film structure helps to obtain smaller grain size and weaker inter-granular exchange coupling interaction in the magnetic layer after annealing process. C atoms' diffusion into Ti underlayer, Co-alloy magnetic layer or grain boundary in magnetic layer plays an important role in the effect of thin C layer insertion on the magnetic property and microstructure of CoCrPt/Ti hybrid recording media.

The FePt single layer films with different thickness were deposited by RF magnetron sputtering on glass and Corning glass substrates, and the L10-FePt films were obtained after the as-deposited samples were subjected to vacuum annealing using different cooling processes. It costs 7 hours for the temperature to decrease from 550 to the room temperature during the natural cooling process, however it just costs 1.5 hours during the fast cooling process.Results show that after annealed at for 1h, the perpendicular coercivity of the FePt single layer films decreases with the increasing of FePt layer thickness, and the FePt 15nm film exhibits a high perpendicular coercivity of 8308 Oe and a low in-plane coercivity of 5141 Oe, which suggests that the film exhibits a high perpendicular anisotropy. The FePt films with nature cooling can obtain larger Mr/Ms values than that with fast cooling.

Pt and Ag underlayers with rough surface structure have been prepared onto glass slides by rf magnetron sputtering and the effects of rough underlayers on the magnetic properties of TbFeCo films have been investigated. It was found that rough Pt or Ag underalyers will increase the coercivity, the saturation magnetization and the Kerr rotation angle, enhance the temperature dependence of magneto-optical characteristics. These results can be explained with the pinning effects introduced by rough interfaces and the decrease of the exchange interaction between Tb atom and transition metal atom. A saturation magnetization of 125emu/cm³ and a coercivity of 8.6kOe of Tb₂₁Fe₆₉Co₁₀/Pt at room temperature could be obtained, doping of the LRE elements such as Sm and Nd could increase the Ms of TbFeCo films with rough underlayers. These films become a candidate for high -density hybrid recording media.

A new photochromic diarylethene bearing a six-membered aryl unit, 1-(2-methyl-5-pheny-3-thienyl)-2-(2-methyl-4- pheny-phenyl)perfluorocyclopentene (1a), was synthesized and its photochromic and fluorescent properties were investigated. Diarylethene 1a changed the color from colorless to violet upon irradiation with 313 nm UV light, in which absorption maxima were observed at 554 nm in hexane and at 578 nm in PMMA film, respectively. This new photochromic system also exhibited remarkable fluorescence switching in the solid state. Finally, rewritable holographic optical storage using 1a was performed. The results demonstrated that the compound was very sensitive responding to 633 nm recording laser, and the recorded holographic images have good contrast.

Spirooxazines (SOs) and spiropyrans (SPs) are typical organic compounds exhibiting photochromism. Compared to SPs, SOs show better fatigue resistance and photostability, which provides a possibility of practical applications in lenses of variable optical density, displays, filters and optical-memory devices. The maximum values of photo-induced birefringence of spirooxazine in poly(methyl methacrylate) (PMMA) films pre-irradiated by ultraviolet light was investigated as a function of He-Ne laser (632.8nm) pumping-beam intensity. A dynamics of photo-induced birefringence was recorded by a linearly polarized double-frequency Nd:YAG laser (532 nm) of 0.1 mW as a probe beam. This material exhibited a competing process between photo-orientation and photo-isomerization. The photo-orientation is predominant when the power density of He-Ne beam is lower; while the photo-isomerization is dominant at relatively high power density of He-Ne beam. An improved phenomenological model, elucidating a competition between photo-orientation and photo-isomerization, was precisely presented. Dynamic holographic recording under linear polarized writing beams at 632.8 nm was performed on spirooxazine doped PMMA matrices assisted by UV light. It was found that dynamics of the optical storage signal intensity in the polymer films were dependent on the thermal stability and aggregation of spirooxazine molecules in PMMA matrices. A theoretical description the formation and eraser of the transient orientation grating, competing with isomerization gratings, agrees well with experimental results. The interaction between the chromophores and matrices was also discussed. It was indicated that spirooxazine-doped polymer films are candidates for reversible optical storage medium.

Three kinds of novel metal(II)-azo complexes based on indandione were synthesized in order to obtain a suitable optical recording medium for blu-ray disc-recordable (BD-R). Smooth thin films of these metal(II)-azo complexes were prepared by spin-coating method. Absorption spectra, thermal decomposition and blu-ray static recording properties of the thin films were investigated. These metal(II)-azo complexes, with absorption peaks at 435 - 444nm wavelength region, have high thermal stability with sharp thermal decomposition thresholds. The results of the blue-ray (405nm) static optical recording test of these metal(II)-azo complexes indicated that high reflectivity contrast (>50%) can be obtained at appropriate laser power and pulse width, and the size of the recording mark on the Co(II) complex film is as small as 200nm at writing laser power of 2mW and pulse width of 300ns. These results imply that metal(II)-azo complexes based on indandione are promising candidates as recording media of BD-R.

Optically induced molecular orientation by photoisomerization of chromophores has been intensively researched with views of application in photonics. We report a new polarization-encoded data storage method in a diazobenzene/MMA copolymer. Two-photon absorption (TPA) of 4-{(2-methacryloyloxyethyl)oxy}-4'-(4-nitrophenylazo)azobenzene/MMA copolymer creates a regularly angle variation of molecular orientation via a trans-cis isomerization process and induces birefringence in the sample. This feature is a key for ultrahigh-density optical data storage. The experiment for two-photon recording and reading was carried out by a homemade two-photon scanning microscope developed based on a confocal laser scanning fluoresce microscope. Linearly polarized femtosecond pulsed laser beam with pulse width 80fs, repetition rate 80MHz and wavelength 800nm was used as recording beam. A polarizer and a half-wave plate were used to control the readout beam polarization state. A Ti: sapphire laser at continuous-wave mode was used for readout process. Experimental results of recording and reading data bits with size of 4 microns and interval of 8 microns were presented. An approximatively linearly relationship between excitation power and the readout signal intensity was observed. The great difference between the signals read out by different polarized laser beams provide a multiple-state way to improve storage density.

A new photochromic diarylethene compound, 1-[2-methyl-5-(3-methoxylphenyl)-3-thienyl]-2-[2-methyl-5-(3- trifluoromethylphenyl)-3-thienyl]perfluorocyclopentene (1a), was synthesized and its photochromism and photo-induced anisotropy was investigated. It showed good photochromism both in solution and PMMA amorphous film by photoirradiation. In hexane, the colorless solution turned to blue with a new broad absorption band centered at 579 nm upon irradiation with 254 nm UV light. The blue colored solution returned to colorless upon irradiation with visible light (λ > 500 nm). The open-ring isomer of 1a exhibited relatively strong fluorescence at 352 nm when excited at 295 nm in hexane. In PMMA film, diarylethene 1a also showed good photochromism. In addition, the result indicated that the compound showed a photoinduced anisotropic phenomenon accompanying the photochromic reaction, which illustrated that the diarylethene can be potentially used as polarization multiplexed image recording medium.

Photochromic symmetrical diarylethenes derivatives 1a-4a bearing different long alkyl chains at 2-position of thiophene rings have been synthesized and their photochromism and kinetics of the photochromic cyclization/cycloreversion both in hexane and in PMMA film were investigated. The results showed that the cyclization/cycloreversion process of these compounds were determined to be the zeroth/first order reaction, and the different long alkyl chains effects on kinetics according to the data of reaction rates both in hexane and PMMA film.

A symmetrical photochromic diarylethene, 1,2-bis-[2-methyl-5-(2,4-fluorophenyl)-3-thienyl]perfluorocyclopentene (1a), has been synthesized. Its photochemical properties, including photochromic behavior and fluorescent features, have been investigated in detail. The compound showed good photochromism both in solution and in solid state. Especially, the diarylethene exhibited a relatively strong fluorescence switches along with the photochromism from open-ring isomers to closed-ring isomers in solid state. When irradiated by UV light, the photocyclization reaction was occurred and the emission intensity of the diarylethene decreased significantly, due to producing the non-fluorescence closed-ring isomers. The back irradiation by appropriate wavelength visible light regenerated its open-ring isomers and recovered the original emission intensity. The cycles of fluorescence switching can be repeated ca. 10 times and the efficiency of photo-switching almost keeps as same as that of original value. The results demonstrated that the diarylethene can potential act as a system for reversible data processing using fluorescence as the detection method.

Five new photochromic unsymmetrical diarylethenes bearing different substitutes have been synthesized. Substituent effects on their optoelectronic properties, including photochromism, fluorescence properties were investigated in detail. The strong electron-donating substituents have effective contributions to the absorption maxima of the closed-ring isomers and the molar coefficients, while the electron-withdrawing substituents can shift significantly the absorption maxima of the diarylethenes to a longer wavelength and increase their cyclization quantum yield. In addition, these diarylethenes exhibited different color (red, purple, blue and green) both in solution and in PMMA film with alternating irradiation by UV/vis light, which can be potentially applied in the devices of full-color display.

A series of photochromic diarylethenes compounds were synthesized and the electrochemistry and electrochemistry reaction mechanism properties were investigated. The cyclic voltammetry tests demonstrated that the colorless open-ring isomers were assigned to the unique oxidation process, but the color closed-ring isomers of these compounds were assigned to two oxidation processes. In addition, the electrochromism of diarylethene compound is observed in solution: The closed-ring reaction can be triggered by electrochemical oxidation, while the open-ring reaction must be photochemically driven. These oxidation processes properties can be useful as the oxidation processes electrochemical switching and the oxidation electrochemical switching properties of these different diarylethene isomers can be potential for electrochemistry data storages.

In this paper we study the coherent transient property of a Λ-three-level system (Ω_d = 0) and a quasi- Λ -four-level system (Ω_d>0). Optical switching of the probe field can be achieved by applying a pulsed coupling field or rf field. In Λ -shaped three-level system, when the coupling field was switched on, there is a almost total transparency of the probe field and the time required for the absorption changing from 90% to 10% of the maximum absorption is 2.9_Γ0 (_Γ0 is spontaneous emission lifetime). When the coupling field was switched off, there is an initial increase of the probe field absorption and then gradually evolves to the maximum of absorption of the two-level absorption, the time required for the absorption of the system changing from 10% to 90% is 4.2_Γ0. In four-level system, where rf driving field is used as switching field, to achieve the same depth of the optical switching, the time of the optical switching is 2.5_Γ0 and 6.1_Γ0, respectively. The results show that with the same depth of the optical switching, the switch-on time of the four-level system is shorter than that of the three-level system, while the switch-off time of the four-level system is longer. The depth of the optical switching of the four-level system was much larger than that of the three-level system, where the depth of the optical switching of the latter is merely 14.8% of that of the former. The speed of optical switching of the two systems can be increased by the increase of Rabi frequency of coupling field or rf field.

A new photochromic diarylethene bears two chiral carbon atoms was designed and synthesized. This compound keeps in liquid state at room temperature which is the first example for 1,2-dithienylalkene derivatives to our knowledge. Owning to the liquid state, this compound undergoes a much faster reversible photochromic reaction than some 1,2-dithienylalkene derivatives in solid state, at ambient temperature. In addition, the fluorescence property and the uses of this compound in photo switches and non-reductive storage material were discussed.

In this paper, we present the architecture and implementation of a virtual network computers' (VNC) optical storage virtualization scheme called VOSV. Its task is to manage the mapping of virtual optical storage to physical optical storage, a technique known as optical storage virtualization. The design of VOSV aims at the optical storage resources of different clients and servers that have high read-sharing patterns. VOSV uses several schemes such as a two-level Cache mechanism, a VNC server embedded module and the iSCSI protocols to improve the performance. The results measured on the prototype are encouraging, and indicating that VOSV provides the high I/O performance.

In this paper, we investigate the reliability in a petabyte scale storage system built from thousands of Object-Based Storage Devices and study the mechanisms to protect data loss when disk failure happens. We delve in two underlying redundancy mechanisms: 2-way mirroring, 3-way mirroring. To accelerate data reconstruction, Fast Mirroring Copy is employed where the reconstructed objects are stored on different OBSDs throughout the system. A SMART reliability for enhancing the reliability in very large-scale storage system is proposed. Results show that our SMART Reliability Mechanism can utilize the spare resources (including processing, network, and storage resources) to improve the reliability in very large storage systems.

In this paper, we design and implement a data disaster recovery system based on storage-virtualization. The data disaster recovery system implements its function through the collaboration of multiple sites in wide-area scope. Each site is an independent data center and data disaster recovery unit. The construction of each site is based on storage-virtualization gateway which is a storage-virtualization platform supporting storage multi-protocol. Therefore, through storagevirtualization gateway's implementation of data replication, failure detection, service switch/takeover among the multiple sites, data disaster recovery could be implemented.

This paper proposes a server-free backup model deploy on Content Aware Storage System (CASS). The CASS is a new type information storage system which consists of three layers. In the middle is content management control layer which is the core layer of the storage system. Compare with host based, LAN based and LAN-Free backup model, this work design a series of models to fulfill server-free backup solution. Thos models includes backup task detective, detective agent, query backup activate condition, semantics derivation, storage resource balancer, de-duplication, copy agent. This server-free backup model not only speeds up the backup operation, but also off-loads the LAN and host computer, ensuring optimum performance and continuous data access on the network.

According to both the Fibre Channel (FC) Storage Area Network (SAN) switch and Fabric Application Interface Standard (FAIS) mechanism, an iSCSI storage controller is put forward and based upon it, an internet Small Computer System Interface (iSCSI) SAN construction strategy for disaster recovery (DR) is proposed and some multiple sites replication models and a closed queue performance analysis method are also discussed in this paper. The iSCSI storage controller lies in the fabric level of the networked storage infrastructure, and it can be used to connect to both the hybrid storage applications and storage subsystems, besides, it can provide virtualized storage environment and support logical volume access control, and by cooperating with the remote peerparts, a disaster recovery storage system can be built on the basis of the data replication, block-level snapshot and Internet Protocol (IP) take-over functions.

Existing security solutions in network storage environment perform poorly because cryptographic operations (encryption and decryption) implemented in software can dramatically reduce system performance. In this paper we propose a cryptographic hardware accelerator on dynamically reconfigurable platform for the security of high performance network storage system. We employ a dynamic reconfigurable platform based on a FPGA to implement a PowerPCbased embedded system, which executes cryptographic algorithms. To reduce the reconfiguration latency, we apply prefetch scheduling. Moreover, the processing elements could be dynamically configured to support different cryptographic algorithms according to the request received by the accelerator. In the experiment, we have implemented AES (Rijndael) and 3DES cryptographic algorithms in the reconfigurable accelerator. Our proposed reconfigurable cryptographic accelerator could dramatically increase the performance comparing with the traditional software-based network storage systems.

With the explosive growth of digital information, storage systems are becoming larger and more complicated. Especially in large scale storage systems, they must be able to deliver satisfactory I/O performance (availability, reliability, etc.) under both expected and unexpected workloads, and handle data with real timeliness requirements. However, typical management methods of mass storage systems cannot meet these requirements. One solution is using Quality of Service (QoS) approaches in object-based storage systems. These QoS approaches include Quality of Storage Service (QoSS) framework and QoSS improvements. After researching the QoS requirements and the various data access characterizations in different applications, we designed a QoSS management framework. And then according to this framework, we gave some improvements to efficiently realize QoSS in object-based storage systems. To demonstrate the effectiveness of our proposed solution, we developed a prototype of Attribute-managed Storage System with QoSS (AM-QoSS) by extending both OSD and iSCSI protocols. The measurement results finally show that the proposed QoS management approach achieves optimization of storage systems, such as higher performance and better guaranteed QoS.

This paper presents a new robust watermarking extract scheme for color image by using scale invariant features transform image correction. A binary watermark image is permuted with sequence numbers generated by a secret key in a spatiotemporal chaos system. Then, the binary image watermark was encoded by Gray code, and then adaptively embedded into low frequency components of discrete cosine transform domain in the original color image's blue channel. In watermarking extract scheme, the scale invariant features of images are extracted, and the match points between the watermarking image and the reference image are found. Then the watermarking image is corrected by affine transform of these match points. Although the watermark is only embedded into the blue channel, the other channel can provide the position information of the image processing operations. By comparing the intensities of the low frequency components of discrete cosine transform domain of the corrected and the original image, the extraction method of the watermark is calculating the probability of detecting '0' or '1'. At last, the watermark is extracted from the corrected image. Experimental results show that the proposed scheme is robust and secure against a wide range of image processing operations such as global affine transformation, filtering and lossy compression.

According to the role of the current large-scale storage system, this paper introduces a novel metadata service strategy that separates read from write for the larger proportion of read. It centralizes control and reduces the access workload through the multi-metadata server architecture of the master/slave mode. Through the sharing of original metadata server to read the response to the large scale to reduce the load on the reading pattern to form a viable structure of the system. It not only can bring the system better scalability and usability, but can well control metadata consistency. Finally, compared to Active/Active structure, Read/Write strategy has shown a relatively good result in the aspect of the access efficiency and System costs. As a service management strategy, it effectively reduces the load of the data access of metadata service.

Metadata service system is a latent access bottleneck in a large distributed storage system. The traditional methods of metadata distribution and management does not take more dynamic load balancing into account especially in heterogeneous MDS(MetaData Server, MDS) cluster, therefore it is very easy to become hotspots . This paper introduces a linear chain load balancing policy based on hybrid method which has both the advantages of the directory subtree partitioning and the pure hashing in MDS cluster. Comparing with traditional methods, it can dynamically distributes and manages metadata according to the workload of every MDS in heterogeneous MDS cluster. Finally it is proved to have good load balancing by analyzing the arithmetic theoretically and simulation test.

Nowadays, content-based network storage has become the hot research spot of academy and corporation[1]. In order to solve the problem of hit rate decline causing by migration and achieve the content-based query, we exploit a new content-aware storage system which supports metadata retrieval to improve the query performance. Firstly, we extend the SCSI command descriptor block to enable system understand those self-defined query requests. Secondly, the extracted metadata is encoded by extensible markup language to improve the universality. Thirdly, according to the demand of information lifecycle management (ILM), we store those data in different storage level and use corresponding query strategy to retrieval them. Fourthly, as the file content identifier plays an important role in locating data and calculating block correlation, we use it to fetch files and sort query results through friendly user interface. Finally, the experiments indicate that the retrieval strategy and sort algorithm have enhanced the retrieval efficiency and precision.

If an intruder uses a stolen account, the authentication sub-system will regard the intruder as a legitimate user. In order to filter out such illegal users, the storage system should be capable of the user activity diagnosis. This paper presents a novel anomaly detection scheme to monitor the user access activities using the artificial immune technique. When an access request violates the access control rule, it is regarded as Non-self, so as to provide some early warning tips to the storage security sub-system. Compared with the NIDS, the proposed scheme targets the anomaly detection at storage level and focuses on the read/write data requests. In the prophase of simulation, a set of optimal parameters of algorithm are fitted according to the mean convergence speed and detection efficiency. The simulation shows the proposed scheme can reach rather high detection rate and low false alarm rate, further validating its feasibility. Thus the storage anomaly detection would strengthen the storage early warning and improve the storage security.

Recently, high-energy consumption has become a serious concern for both storage servers and data centers. Recent research studies have utilized the short response times of multiple speed disks to decrease energy consumption. However, very few manufactures can produce the multiple speeds hard disk because of its complexity. The main limitation to MAID system is that we must assume the frequently accessed data is less than 5%, in fact, in most strong coupling system, the data can't be cached due to the access pattern and moreover the first accessed data which are usually frequently accessed are not cached, as a result, system performance is heavily degraded. In this paper, we propose the new storage system called saving energy RAID (SERAID), in which we place the frequently accessed data into solid state disks (SSD) and place the less frequently accessed ones into conventional hard disks (CHD). Because the energy consumption is very low and the random read/write rate is very fast in SSD, we can get high availability and high saving energy RAID system at the expense of very few costs. The simulation result shows that the random write performance of SERAID is 10 times rapid than those of traditional RAID and the random read performance of SERAID is 5 times rapid than those of conventional RAID. Besides that, the mean energy consumption of SERAIDsystem is lower than that of traditional RAID.

As a new generation of high-performance distributed storage system, object-based storage system is being developed to support high-performance computing environments. In the petabyte-scale object-based storage system, reasonable data distribution and parameters configuration can improve system performance and availability. To make the system performance evaluation work easier, we propose an approximate parameters analysis method to build performance model. We firstly model the whole storage system's architecture based on closed Fork-Join queue model; using our system architecture model, we then deduce an approximately analytical expression with erasure codes and replicas to predict the storage system's mean response time under various workloads simulating the real-world condition. Finally, a large number of comparison experiments validate our approximately analytical expression of system performance, and proved that our analytic method is appropriate to build performance model for object-based storage system.

This paper introduces a storage system which can adjust its storage strategy automatically according to the current running environment, evolutionary storage system (ESS). In the evolutionary processes, ESS can automatically choose one system organizing strategy which fits for the current running environment best, to keep the dynamic balance of the whole system. ESS can always adapt to the request of current application, no matter the storage device is out of date or not. So the most remarkable character ESS shown is that the system will be better and better along with the running. The performance of ESS will increase gradually with the evolution. Three evolutionary ways, system physical structure evolution, system logical structure evolution and data distribution evolution were described and demonstrate separately.

The paper proposed a novel authentication method for networked storage using artificial immune technique, addressing the storage security issue. Most authentication sub-systems adopt the positive identification to judge the user identity, however if an intruder obtains some account information, he may crack the authentication sub-system using Rule-based Attack and do harm to the storage system. Aiming at this problem, we designed a negative authentication to improve entrance security of storage system, where the identification data are stored in Non-self space so as to prevent the intruder from discovering any account information. Additionally, the negative authentication sub-system can filter out the unauthorized users. The experimental results showed that the proposed authentication method could be efficient in detecting unauthorized user, so the negative authentication sub-system may improve the storage security.

With the growing scale of the computer storage systems, the likelihood of multi-disk failures happening in the storage systems has increased dramatically. Based on a thorough analysis on the fault-tolerance capability on various existing storage systems, we propose a new hierarchical, highly reliable, multi-disk fault-tolerant storage system architecture: High Availability Object Storage System (HAOSS). In the HAOSS, each object has an attribute field for reliability level, which can be set by the user according to the importance of data. Higher reliability level corresponds to better data survivability in case of multi-device failure. The HAOSS is composed of two layers: the upper-layer and the lower-layer. The upper-layer achieves the high availability by storing multiple replicas for each storage object in a set of storage devices. The individual replicas can service the I/O requests in parallel so as to obtain high performance. The lower-layer deploys RAID5, RAID6 or RAID_Blaum coding schemes to tolerate multi-disk failures. In addition, the disk utilization rate of RAID_Blaum is higher than that of multiple replicas, and it can be further improved by growing the RAID group size. These advantages come at the price of more complicated fault-tolerant coding schemes, which involve a large amount of calculation for encoding and cause an adverse impact on the I/O performance, especially on the write performance. Results from both our internal experiments and third-party independent tests have shown that HAOSS servers have better multi-disk- failure tolerance than existing similar products. In a 1000Mb Ethernet interconnection environment, with a request block size of 1024KB, the sequential read performance for a HAOSS server reaches 104MB/s, which is very close to the theoretical maximum effective bandwidth of Ethernet networks. The HAOSS offers a complete storage solution for high availability applications without the compromises that today's storage systems require in either performance or fault-tolerance.

This research proposes a new Storage Data Gateway (SDG) on Content Aware Storage System (CASS). The CASS consists of storage application service, content auto-tiering storage; management and control sever which is the Content Management Server (CMS). The system gives each stored object a unique content address, derived from the content itself. The physical location of stored information becomes irrelevant to users. The CMS takes advantage of the tier data architecture and decides data migration strategists. But the CMS will be overload if the system assigns the backup and data migration work to it on LAN-based model. That server does not need to control each data duplication or migration. It will be free with Sever-free model. The system needs some special device to transfer data between highspeed storage node and low-speed storage node and intermix FC storage node and IP storage node with content information instead of the responsibility of CMS like on LAN-based model. That device is a new type of SDG which needs content aware, high bandwidth, strong computing ability, and high reliability. According to those requirements, we design the Content Aware SDG (CA-SDG) based on ATCA specifications. Advanced Telecommunications Computing Architecture (ATCA) is a new series of PICMG specifications, targeted to requirements for the next generation of carrier grade communications equipment. This series of specifications incorporates the latest trends in high speed interconnect technologies, next generation processors and improved reliability, manageability and serviceability. The hardware system of CA-SDG consists of two compute units (one unit deal with commands from CMS, the other interpreter data between storage nodes), two network switch units (one is redundant), two network interface units (one group units interconnect application service layer, and the other group provide the communication of heterogeneous storage nodes), one local storage unit and one manager unit. The network switch units and compute units make up of a dual star switch network. Network interface units and local storage units which are in the form of AMC card connect Compute unit through PCI-E bus, supplying extended network interface and local storage capacity to compute unit. The manager unit is responsible for the management of whole CA-SDG device.

Most existing data backup systems are too professional to understand. It usually needs time-consuming training for a man to learn how to configure the backup system to make sure it works well. This has greatly affected the data backup systems popularity. In this paper, we design and implement an embedded backup system which uses a hard disk and an embedded development board to integrate a backup-server and a backup-client, increment backup in non-fixed block-level, and provides a friendly Web UI (user interface) to the end-user. The final evaluation shows that the system is easily, efficiency, storage-space saving and network-bandwidth saving, and it can be used in many situations.

RAID systems provide both improved capacity and performance as compared to single disk by striping data to multiple disks, and improve reliability efficiently by redundancy techniques, now RAID becomes key storage device for massive storage system. There are two ways to implement the RAID system: the first is to implement as a software subsystem under PC platform, the second is to implement as a hardware controller. The second one is more common. We have designed and implemented a RAID hardware controller, which called DSDM-FC2000. This paper discusses three kinds of bottlenecks of the DSDM-FC2000 RAID hardware controller: PCI transmission bottleneck, memory access bottleneck and CPU computation bottleneck, and then presents an optimized hardware XOR algorithm which can improve the RAID performance efficiently. Finally this paper gives some advises on designing new generation RAID controller hardware.

The distribution of metadata is very important in mass storage system. Many storage systems use subtree partition or hash algorithm to distribute the metadata among metadata server cluster. Although the system access performance is improved, the scalability problem is remarkable in most of these algorithms. This paper proposes a new directory hash (DH) algorithm. It treats directory as hash key value, implements a concentrated storage of metadata, and take a dynamic load balance strategy. It improves the efficiency of metadata distribution and access in mass storage system by hashing to directory and placing metadata together with directory granularity. DH algorithm has solved the scalable problems existing in file hash algorithm such as changing directory name or permission, adding or removing MDS from the cluster, and so on. DH algorithm reduces the additional request amount and the scale of each data migration in scalable operations. It enhances the scalability of mass storage system remarkably.

Recent advances in large-capacity, low-cost storage devices have led to active research in design of large-scale storage system built from commodity devices. These storage systems are composed of thousands of storage device and require an efficient file system to provide high system bandwidth and petabyte-scale data storage. Object-based file system integrates advantage of both NAS and SAN, can be applied in above environment. Continuous data protection (CDP) is a methodology that continuously captures or tracks data modifications and stores changes independent of the primary data, enabling recovery points from any point in the past. All changes to files and file metadata are stored and managed. A CDP method in Object-based file system is presented in this thesis to improve the system reliability. Firstly, we can get detail at byte level of every write request because data protection operates at the file system level. It can consume less storage space. Secondly, every object storage server can compute the recovery strip data object independently to decrease the recovery time. Thirdly a journal-like metadata management way is introduced to provide metadata optimization for CDP.

With the rapid development of massive storages, traditional RAID of single-protocol is increasingly unable to satisfy the various demands of users. For the purpose of keeping down the investment of storages, we propose a multi-protocol RAID that utilizes existing storage devices. The multi-protocol RAID achieves the integration of storage via managing the disks of different interfaces. This paper presents a framework of multi-protocol RAID and a prototype implementation of it, i.e., the proposed multi-protocol approach can not only unify the storage devices of different types, but also provide different access channels (e.g. iSCSI, FC) to manage the heterogeneous RAID system, thus achieving the goal of centralized management. Our function tests validate the feasibility and flexibility of the proposed RAID system. The comparison tests indicate that the multi-protocol RAID can attain even higher performance than that of the single-protocol RAID, especially the aggregated bandwidth.

Electrical, thermal and crystallization properties of 20at.% Si-doped Sb2Te3 film were investigated and compared to those of conventional Ge₂Sb₂Te₅ film by annealing temperature-dependent resistivity measurement, differential scanning calorimetry (DSC) and in situ time-dependent resistance measurement at various isothermal annealing temperatures. The resistivity of this doped Sb₂Te₃ film after 400 °C annealing is nearly ten times that of Ge₂Sb₂Te₅ film and its melting temperature is about 100 °C lower. The resistivity ratio can reach 10⁶ during the phase transition, accompanied with a smaller thickness change of 1.7% in contrast to that of Ge₂Sb₂Te₅ film of 6.8%. Crystallization temperature of 20at.% Si-Sb₂Te₃ film is 271 °C and maximum temperature for a 10-year lifetime is estimated to be 144 °C with crystallization activation energy of 3.65 eV, which promises better data retention than Ge₂Sb₂Te₅ film. Micrometer-sized phase-change memory devices were also fabricated and examined. Lower power consumption is obtained in the RESET operation of the memory device using 20at.% Si-Sb₂Te₃, which should be attributed to higher crystalline resistivity and lower melting temperature of the film.

Sheet resistance of laser-irradiated Ge₂Sb₂Te₅ films prepared by magnetron sputtering was measured by the four-point probe method. With increasing laser power the sheet resistance underwent an abrupt change of four orders of magnitude (10⁷→10³ Ω/sq) at about 580mW , x-ray diffraction studies of the three samples before, at and after the abrupt point revealed the phase change process of the Ge₂Sb₂Te₅ thin films from amorphous to crystal states. Optical constants of the three samples were measured by ellipsometry. Based on the experimental results, the relationship between the electrical / optical properties and the structure of the Ge₂Sb₂Te₅ thin films is discussed and it is shown that optical-electrical hybrid data storage may be realized using optical writing and electrical reading.

Sb-rich SiSb thin film was recently reported as a promising phase change meromy material. In this paper, optical and structural properties of as-deposited amouphous and laser-annealed crystalline Sb-rich SiSb thin films are studied and compared with pure Sb thin film. Sb and Si₁₅Sb₈₅ thin films were deposited on polycarbonate substrates by magnetron sputtering. Laser initialization in pure Sb and Si₁₅Sb₈₅ thin films were performed with phase-change optical disc initializer. Reflectivity Spectrum and XRD analysis were performed on as-deposited and initialized Sb and Si₁₅Sb₈₅ thin films. The influence of Si doping on its optical and structural properties are discussed and qualitatively explained by a distorted structure model.

Phase transition kinetics of Sb₂Te₃ phase change thin films was investigated in this paper. Sb₂Te₃ thin films, with thickness of ~100nm, were deposited on K9 glass substrates by DC magnetron sputtering with an alloy target. The crystallization kinetics of Sb₂Te₃ thin films under isothermal and non-isothermal annealing was analyzed by a home-made in situ temperature-dependent reflectivity tester. From the heating rate dependences of phase transition temperatures, the activation energy was derived. The obtained values of the Avrami indexes indicate that a two dimension growth crystallization mechanism is responsible for the amorphous-crystalline transformation of Sb₂Te₃ phase change thin films. Although phase transition of Sb₂Te₃ thin film is confirmed to be continuous in a larger temperature range, but short laser pulse can easily trigger its crystallization process and form clear and confined crystalline marks.

High-density phase change material (PCM) array is considered to be an efficient method to decrease operation voltage and power of phase change random access memory (PCRAM). In the paper, the Si₂Sb₂Te₅ (SST) array was fabricated by UV-imprint lithography (UV-IL) and the memory array with 18M/Inch² were constructed. Structural transformation of SST film in heating process was in situ studied by using time-resolved X-ray diffraction. The threshold current and threshold voltage for SST based memory cell are 9.9μA and 0.23V, respectively. After 20ns pulse width inspired, Set/Reset switching operation was achieved and the resistance ratio reached 34. The results show that the SST have potential application in the low-voltage, high-speed storage. The outstanding performance of SST and the new structure enables it to become the new storage devices.

"Quality requirements and handling regulation of archival optical disc for electronic records filing" is released by The State Archives Administration of the People's Republic of China (SAAC) on its network in March 2007. This document established a complete operative managing process for optical disc data storage in archives departments. The quality requirements of the optical disc used in archives departments are stipulated. Quality check of the recorded disc before filing is considered to be necessary and the threshold of the parameter of the qualified filing disc is set down. The handling regulations for the staffs in the archives departments are described. Recommended environment conditions of the disc preservation, recording, accessing and testing are presented. The block error rate of the disc is selected as main monitoring parameter of the lifetime of the filing disc and three classes pre-alarm lines are created for marking of different quality check intervals. The strategy of monitoring the variation of the error rate curve of the filing discs and moving the data to a new disc or a new media when the error rate of the disc reaches the third class pre-alarm line will effectively guarantee the data migration before permanent loss. Only when every step of the procedure is strictly implemented, it is believed that long-term reliability of the data storage on optical disc for archives departments can be effectively ensured.

Optical disk systems are still widely used in players in consumer electronics and automotive applications, although more and more audio and video contents are played from other medias such as flash memory and hard disk drive based devices. There are various architectures with the integrations of audio and video (A/V) decoders and optical disk servo components to reduced product BOM cost. Some issues are addressed for designing optical disk playing modules into an audio or video products. Servo implementation including tracking, seeking and rotating control needs to consider the characteristics of low cost mechanisms and non-ideal disks. When optical disk systems are used in portable or moving environments, the approaches from servo control side and electronic can be helpful for anti-shock. Special handlings to defect disks are important to playability.

Because Toshiba quit the competition, there is only one standard of blue-ray disc: BLU-RAY DISC, which satisfies the demands of high-density video programs. But almost all the patents are gotten by big companies such as Sony, Philips. As a result we must pay much for these patents when our productions use BD. As our own high-density optical disk storage system, Next-Generation Versatile Disc(NVD) which proposes a new data format and error correction code with independent intellectual property rights and high cost performance owns higher coding efficiency than DVD and 12GB which could meet the demands of playing the high-density video programs. In this paper, we develop Low-Density Parity-Check Codes (LDPC): a new channel encoding process and application scheme using Q-matrix based on LDPC encoding has application in NVD's channel decoder. And combined with the embedded system portable feature of SOPC system, we have completed all the decoding modules by FPGA. In the NVD experiment environment, tests are done. Though there are collisions between LDPC and Run-Length-Limited modulation codes (RLL) which are used in optical storage system frequently, the system is provided as a suitable solution. At the same time, it overcomes the defects of the instability and inextensibility, which occurred in the former decoding system of NVD--it was implemented by hardware.

The NVD(Next generation Versatile Disc) OPU(Optical Pick-Up),based on general red light, is able to read a new type of disk which has 15 GB capacity with 2 layers on one side. The linear span of the focus error signal of original NVD OPU light path is shorter than the requirement proposed by the electron servo system. Increasing the thickness of the tilted-parallel-plate to broaden the linear span will increase the coma aberration which will deteriorate the servo accuracy. Furthermore, the thickness of the tilted-parallel-plate is related to the coexistence of DVD and CD servo signal. Therefore, an aberration-compensated and multi-freedom servo lens for NVD OPU is necessary. The servo lens proposed in this paper is a single lens, which the first surface is a combination of cylindrical surface and tilted surface, and the rear surface is a common spherical surface. According to the conversion of Zernike-to-Seidel wavefront aberration, a given amount of astigmatism will be achieved by bending the curvature of the cylindrical surface to broaden the linear span, and the coma will be corrected by the tilted surface. The function of the spherical surface is guaranteeing the coexistence of DVD and CD servo signal. Finally, the specification of the servo lens and simulation result of the whole system will be addressed.

Measurement technology plays an important role in the area of optical storage, a multifunctional quasi-dynamic static optical recording tester, which can also be used as nanometer laser direct writing lithography system, is designed and constructed for optical storage in this paper. The primary characteristics of the system are presented in detail, some experimental results are also given to show that the tester perform successfully, acting as a research platform for both optical storage and laser direct writing lithography.

Nowadays, high-density disc and high-speed optical disk drive have become popular as optical disc has many merits such as cost effectiveness, high data transfer rate, large storage capacity, removability and compatibility. In this paper, we presented a compatible optical pickup actuator for next generation versatile disc (NVD) system. This actuator has high AC sensitivities and good 2nd resonance frequency through finite element method (FEM), and the actuator model properly satisfied the specifications for NVD system. The FEM analyses method is successfully applied to design the optical pickup actuator.

A novel design of physical format coding system (PFCS) is presented based on Multi-level read-only memory disc (ML ROM) in order to solve the problem of low efficiency and long period of disc testing during system development. The PFCS is composed of four units, which are 'Encode', 'Add Noise', 'Decode', 'Error Rate', and 'Information'. It is developed with MFC under the environment of VC++ 6.0, and capable to visually simulate the procedure of data processing for ML ROM. This system can also be used for developing other optical disc storage system or similar channel coding system.

Multilevel modulation coding is the core technology for multilevel optical storage. The technology is employed to increase the capacity of the read-only disc with no change on original recording symbols size. With the combination of multilevel modulation and the run-length limited modulation, short run-length with low levels can form long run-length with high levels while it also suitable for long run-length by short run-lengths. And the DC-suppression can be controlled by the allowance of long run-length without sacrifice effective bits. This double-modulation scheme not only can improve coding efficiency, but also can greatly increase the recording density. In this paper, the theory of multilevel run-length limited modulation coding is discussed. And a high rate of 6/7, five level (1,8) code scheme is proposed. This scheme can increase the recording density compared to that in of DVD. Therefore, it is expected that this proposed scheme could be used for the next high-density multilevel run-length limited modulation optical storage system.

In this paper, we study the special requirements of a special storage system: streaming media server, and propose a solution to improve I/O performance of RAID storage system. The solution is suitable for streaming media applications. A streaming media storage subsystem includes the I/O interfaces, RAID arrays, I/O scheduling and device drivers. The solution is implemented on the top of the storage subsystem I/O Interface. Storage subsystem is the performance bottlenecks of a streaming media system, and I/O interface directly affect the performance of the storage subsystem. According to theoretical analysis, 64 KB block-size is most appropriate for streaming media applications. We carry out experiment in detail, and verified that the proper block-size really is 64KB. It is in accordance with our analysis. The experiment results also show that by using DMA controller, efficient memory management technology and mailbox interface design mechanism, streaming media storage system achieves a high-speed data throughput.

Scaleable storage system has contradiction between usability and extendibility, so a suitable data placement scheme is given to solve this problem in scaleable object storage system. This scheme includes data placement algorithm and data reorganization algorithm. The data placement scheme has the following characteristics: the data placement algorithm uses key as the seed of random data generator to map data objects to storage nodes, which can provide reliable accessing to scaleable storage system. The data placement algorithm distributes data objects uniformly among storage nodes, which can improve I/O performance by accessing simultaneously several nodes. The data reorganization algorithm migrates data only from old storage nodes to added storage nodes (or from withdrawn nodes to surplus nodes), which can improve usability by reducing data migration. At last, the two algorithms have less cost of time and space, which is suitable to large-scale storage systems.

Since the first commercial optical disc came out in 1970s, many kinds of optical disc with peculiar format were invented in sequence, and most of them have win tremendous successes in commercial use all over the world. Each format has its own characteristics on disc structures, optical parameters, data coding, physical property, storage capacity and more. Here we give a review on the optical disc formats which represent the mainstream optical disc development since 1970s. We will discuss on the optical disc formats on basic parameters of optical disc, their application background, their innovation advantages, their compatibilities and related views.

Nowadays digital information is growing increasingly faster than ever before and data storage has been becoming an indispensable branch of computer science and technology. Based on a review of the current development of data storage, a novel view on the classification and feature of data storage has been put forward. Several ideas on the mass and high density are analyzed. The theory and key technology of holographic storage is introduced from the perspective of application.

A new system of observing and measuring magnetic domain is designed in this paper. The system includes three parts - the principal part of observing and measuring the magnetic domain, the crate controller and the computer used to control the whole system. The principal part consists of x-y scanner, z scanner, digital source meter, ion blower, optical microscope, and giant magnetic resistor (GMR) magnetic head. The GMR magnetic head in this system can be intact after a long-time running in the ordinary laboratory by taking some measures of eliminating electrostatic discharge (ESD). We successfully observed the magnetic domain written in a nanomagnetic material and measured the size of the magnetic domain by use of the new system. The system is very simple and inexpensive, and it has high resolution and signal-to-noise.

The lens actuator is one of the most important mechanical-electrical components in optical disc systems. It is used for adjusting the attitude and position of the objective lens. When it works, the resonance vibration including the first resonance and higher order resonance will happen near the resonance frequency, which will weaken the servo control capability, thus additional damper glue is necessary to restrain the resonance magnitude. In order to obtain better damping performance, the location of the damper glue and the structure of the damping filler are very important to control the resonance magnitude. In this paper, according to the flow feature of the damper glue, damping models in focusing, tracking and tilting direction are established with the help of Oseen flow equation, and equivalent damping coefficients are derived. Some samples with the design parameters are fabricated and tested, the damping coefficients obtained form the experiment are compared with the theoretical results, which shows the validity of the proposed fluid model and the design method.

During the design process of Blu-ray Disc Optical Pick-Up (BD OPU), the optical system design plays a significant role, and the collimator lens design is especially important. According to the PW optical design formulas, this paper calculates the initial parameters of collimator lens. It chooses the triplet type collimator lens instead of aspheric lens to design in order to reduce the manufacture difficulty according to the real situation in China. And then based on the initial parameters of collimator lens, the paper optimizes the triplet collimator lens to reach a good quality effect of parallel beam. At last it puts these design data into manufacture and adjusts the distance between the LD and the collimator lens by using the sleeve mechanism structure to see the real effect of collimating. Finally the assembly experiment of whole BD OPU validates these design that it can be used in BD OPU very well.

There are four kinds of semiconductor components in Optical Pickup Units (OPU), i.e. Laser Diode Driver (LDD), Photo Detect IC (PDIC), Front PDIC (FPD) and High Frequency Modulator (HFM). Two types of LDD described are direct-drive LDD and write strategy built-in LDD. A PDIC is a light to electrical energy converting device, which includes photodiodes and transimpedance amplifiers. FPD is a power monitor PDIC. It has some similarity to PDIC but the requirements differ from PDIC. HFM is used during read by impressing a high frequency current on a DC current to drive the laser diode to let it emit a discontinue power signal. This paper gives overview of these four ICs and highlights on key design, application and testing issues.

Hybrid Magneto-Optical Recording is a potential data storage technology in the future informational society. To construct a research platform for hybrid recording, a dynamic testing system is designed and built in this paper, in which 406.7nm blue laser is used for recording and 655nm red laser for focus servo. With high modularization, the computer serves as the control core for the laser external modulation, focus servo, and sample plate spinning. Each module and its function are discussed in detail in the paper. Experimental results are also given to verify the stable and smooth performance of the system, in which the key obstacle, vibration noise, is successfully surmounted.

The traditional method of power spectrum computation of modulation code is that firstly computing the autocorrelation function of the code, and then taking Fourier transform of the autocorrelation function to get the power spectrum. Unfortunately, it is difficult to get autocorrelation function according to the coding methods, therefore, the traditional method is not fit to compute power spectrum of practical RLL code. In this article, we use a method that is based on onestep state-transition matrix is much simpler, which all the parameters can be computed according to RLL coding methods. We use the method to compute the power spectrum of a new modulation code called RLL (2, 12; 8, 15), and evaluate the spectrum performance of the new modulation code according to the power spectrum. Meanwhile, we improve the new modulation code in order to get a better spectrum performance.

This article introduces DVD Download specification and Manufacturing On Demand (MOD) system firstly. Then it will show a designed MOD system and analyze the function of each part in it. In this system, we need to combine two DVD's files into one disc automatically, so in the last part, the article shows work on this problem and achievement up to now.