This paper reported that, using a directly modulated lasers (DMLs) with a ?/8 phase-shifted distributed feedback (DFB) grating, isolator-free 2.5-Gb/s transmission over 138-km non-dispersion-shifted fiber (NDSF) was demonstrated with ?20-dB external optical feedback. The power penalty was 1.7 dB for a bit error rate (BER) of 10-10. Further potential for their low chirp characteristics was also demonstrated by error-free transmission over 200 km without optical feedback. Uncooled transmission performance at 80°C was also investigated. A low power penalty of less than 1.0 dB for a BER of 10-10 was obtained in transmission over 60 km. The good experimental results are due to the characteristics of low chirp and optical feedback resistance that originate from the negative feedback effect of mirror loss (FEML) in ?/8 phase shifted DFB-LDs. Also discussed in this paper is the design of coupling coefficient ?L and of detuning ?? between oscillation wavelength and gain maximum since these parameters strongly affect the DMLs’ transmission characteristics.

The dual-wavelength operation with tunable mode separations for InGaAs-GaAs ridge waveguide DBR lasers are studied. The DBR lasers consist of a common gain section and two separate DBR section. The two DBRs utilize uniform gratings with the same Bragg period, resulting in a single nominal lasing wavelength. Dual-wavelength operation is achieved by simultaneously lasing the front grating mode and the back grating mode. By employing a spacing section between the two DBR gratings and applying a tuning current on it, the interaction between two mode is minimized and the control over the wavelength turning is greatly improved. Three device dimensions were investigated. The relationships between two-mode operation parameters and biasing/tuning conditions for each type are analyzed. The promising applications of this multi-wavelength optical source, such as in optical generation of millimeter-wave, are discussed.

The vertical-cavity surface-emitting lasers (VCSEL) operating in the spectral range near 850 nm usually utilize GaAs/AlGaAs as the active layer materials. In this work, in addition to the traditional unstrained GaAs/AlGaAs semiconductor laser, the characteristics of the strained InGaAs/AlGaAs vertical-cavity surface-emitting laser and the distributed Bragg reflectors (DBR) used in this semiconductor laser are investigated with a PICS3D (abbreviation of Photonic Integrated Circuit Simulator in 3D) simulation program. The simulation results show that the strained InGaAs/AlGaAs VCSEL has a better optical performance than that of the traditional unstrained GaAs/AlGaAs VCSEL. That is, when compared with the unstrained GaAs/AlGaAs quantum well structures, the strained InGaAs/AlGaAs VCSEL has a higher stimulated recombination rate, a lower threshold current, a higher main-side mode suppression ratio, and a higher characteristic temperature, which might be owing to its narrower well width and smaller carrier effective masses.

A dynamic gain control (DGC) technique for the multi-wavelength-pumped fiber Raman amplifier (FRA) is presented. It introduced an all-optical feedback to inject a portion of the signal power into the system by using a variable attenuator. The stable performance of the proposed gain-clamped FRA was simulated and the noise performance was also discussed.

A screwdriver-like fiber end to couple the light power of laser diode array(LDA) into multimode fiber is presented. The coupling efficiency formula of such coupling system is given, and the numerical evaluation show that the theoretical coupling efficiency could be as high as 83% without an antireflection coating on the fiber end face. This method can be easily fabricated and has large tolerance.

We demonstrate a novel approach for generating a stable and low polarization-sensitive mode-locked fiber ring laser by using a low-cost Fabry-Perot laser diode (FPLD) as both the intracavity mode-locker and the band-pass filter. The FPLD pulses is seeded into a close-loop semiconductor optical amplifier (SOA) based fiber ring laser for harmonic and rational harmonic mode-locking operation. The SOA biased at 65 mA and 18°C combines with an intracavity optically feedback-injected 1.3 ?m FPLD biased at 9.4 mA (below threshold current) and 23°C via some optical couplers. Picosecond optical pulse with side-mode suppressing ratio of greater than 12 dB are obtained, the measured lindwidth at 3-dB and 10-dB decay are observed to maintain at about 0.04 nm and 0.14 nm, respectively. Narrow-linewidth operation of the SOAFL with optical pulsewidth of 42.1 ps and wavelength tuning range of about 10 nm at repetition rate of 13 GHz has been demonstrated. The optically injection mode-locking scheme also has shown to exhibit low supermode noise, higher average output power and good stability. The optical output power under harmonic mode-locked scheme is about 297 ?W. The fluctuation in output power, the SSB phase noise at 1 kHz offset frequency, and the calculated rms timing jitter within the integral region from 0 Hz to 1 KHz are ± 2.5 ?W, -82.4 dBc/Hz, and 1.0 ps, respectively.

Using the combined crystal Cr4+:YAG -Nd3+:YAG pumped by LD, the selfQ-switched laser pulses are obtained. The combined crystal with 8mm long and 1mm diameter is doped with 0.2% Cr4+ in one side and 1.1% Nd3+ in the other side. As the gain medium and the saturable absorber simultaneously in one material, this laser possesses a compact structure and high efficiency. Using the Laser diode CW pumping Cr4+:YAG -Nd3+:YAG single crystal micro-cylinder, the self Q-switched laser pulses with the pulse width of iOns and the pulse repetition rate of 10KHz are obtained. The average output power is I 8mW. From the rate equations considering the saturable absorption the pulse width and repetition rate vs. pump power are theoretically calculated. From this theory the pulse duration and output power of single pulse are independent of the pumping power, but the repetition rate almost linear increased with the pumping power. These results agree with the experimental measurements.

A couple system including collimation, shaping and focusing parts has been designed for the pumping demand of Nd:YVO4 laser, based on the analysis of the beam output characteristic of high power laser diode line array and the wave-front theory. A practical result for the design is given out. Tests about the performance of the coupler system have been carried through. It is proved that this couple system is successfully used and can lead to high transition efficiency and fine quality laser beam.

Using a Cr4+:Nd3+:YAG monolithic microchip pumped by a Laser Diode (LD), the self Q-switched laser pulses are obtained. The resonator is made up directly from both parallel surface of the Cr4+:Nd3+:YAG microchip. There are two kinds of way to pump the microchip by LD. In the first case, the Cr4+:Nd3+:YAG monolithic microchip pumped by LD with CW operation. The output self Q-switched laser pulses with the repetition rate of 2.78kHz and pulse width of 6ns are obtained. In the second case, the Cr4+:Nd3+ :YAG microchip is pumped by LD in the pulsed operation with pre-pumping. The Q-switched output laser with a controllable repetition rate and pulse width of 8ns is achieved. In this case, the LD is driven with a weak modulated current over the direct base current which is near the threshold. The base cunent is modulated by prearranged repetition rate of 1~100Hz. With such a pulse operation, the output laser pulse with the same repetition rate can be obtained. This monolithic microchip laser possess higher transform efficiency, narrow pulse width and controllable repetition rate.

Nowadays laser diode pumped solid-state laser is becoming more and more attractive to numerous applications. In Gyroscope, because of its solid-state, high gains and other merits, Laser Diode Pumped Solid-State Ring Laser (DPSSRL) has gained much attention from researchers. The bi-directional DPSSRL using Nd:YVO4 that is never reported as far as we know has been approved in our experiment. The most obvious application ofthis kind ofDPSSRL is in the gyroscope. But DPSSRL has its natural tendency to operate in multiple-longitudinal-mode that will affect the precision of gyroscopes dramatically. So a novel longitudinalmode analysis and selection of DPSSRL is performed. In this analysis a Fabry-Perot etalon is added to the settings of a bi-directional operation of DPSSRL. And the theoretical result is single longitudinal mode. In this paper the bi-directional DPSSL experiment configuration is presented. The bi-directional singlelongitudinal- mode DPSSRL modal using Nd:YVO4 have been developed. In order to get a good performance in the experiments, the beam size ofthe laser in the cavity with and without the crystal has been calculated.

The experimental research on diode-pumped solid-state ring laser (DPSSL) is reported in this paper. The research target is to develop a new style optical gyroscope. The ring cavity is a plane, 8-shape 4-mirror laser resonator. Nd:YVO4 crystal is exploited as a laser media which is longitudinally pumped by a 2w laser diode. An optical delay path attached to the cavity is composed of a beam splitter and a prism. The bidirectional traveling waves partly output from one of the flat mirror and one directional beam interferes with the other on a photo detector with optical delay. The resonator design is discussed; the pump power threshold is about 600mW. We obtain the bidirectional continuous TEM00 mode outputs and their interfering pattern. In the experiment, Sagnac effect is watched, which indicates that the DPSSRL can be used as optical gyroscope.

We review the properties of ordered InGaAs QDs arrays, which are formed by self-organization mechanism on GaAs (311)B substrate. We show that the QDs exhibit remarkably different characteristics compared to the more commonly studied InAs QDs grown on GaAs (00 1) substrate. In addition, some recent results of our strain-compensation growth of InAs QDs stack structures on InP (311)B substrate are presented. The stacked InAs QDs on InP (311)B substrate show strong photoluminescence emission at > 1.55µm at room temperature, which is thereby considered to be promising for the next generation fiber-optic communication devices.

The solid-source molecular beam epitaxy (SSMBE) technology using valved cracker cells is one of the most promising techniques for epitaxial growth of high-quality phosphorus-containing compound semiconductors. This novel technology is transplanted successfully onto a homemade MBE system and is studied roundly. The growth of 1.55-µm-wavelength- range strained and strain-compensated InAsP multiple quantum well (MQW) structures are investigated. A low growth temperature or large V/III flux ratio is found to be favorable for attaining a high structural quality of highly strained MQW structures, and the growth temperature has a critical effect on the sample's optical property. It is also found that an intermediate InP layer of several monolayers, which is inserted between the well and the barrier, is necessary to improve the quality of strain-compensated MQW structures. The measured photoluminescence (PL) fullwidth at half-maximum (FWHM) of 18.7 meV and 17.2 meV for stained and strain-compensated MQW at room temperature are among the best reported to date for 1 .55-µm-wavelength MQW laser structures. Finally, broad-area (BA) separate confinement heterostructure (SCH) MQW lasers are fabricated, and the threshold current density is measured to be 1.4 kA/cm2. This is the first report, to the best of the authors' knowledge, on a 1.55-µm-wavelength-range strained lnAsP / InGaAsP MQW laser structure grown by SSMBE.

A dry-etching process for laser fabrication with vertical, smooth, and flat facets was developed. Using this optimized chemically assisted ion-beam etching (CAIBE) process, unstable-resonator lasers were fabricated and investigated. Such a device exhibits an optical output power of 1.3W at 2A pump current without thermal roll over or catastrophic optical mirror damage (COMD). A differential quantum efficiency of 60% and a threshold current density of 225A/cm2 was measured. Virtual source sizes are in the range of 5 µm (FWHM). More than 80% of the intensity of the virtual sources is included in the main lobe. The position of the virtual source inside the laser is located 340?345 µm behind the output facet and almost independent on pumping current. The brightness of such laser devices is about one order of magnitude higher than the brightness of broad-area lasers and therefore suitable for single-mode ber coupling.

Low-coherence optical tomography (OCT) is a novel technique with high resolution for rapid, noninvasive imaging in living biological tissues. With this technique, a thin "optical section" within a thick biological specimen can be obtained. In this paper, basic principle of OCT is described. The emphasis is on the light source which is one of the most important parts in OCT system. OCT system needs wide-spectrum (in the other words, low-coherence) light source, the obtainable high resolution is directly related to the choice of light source. Appropriate light source can satisfy requirement of OCT system, otherwise inappropriate light source will degrade the resolution of OCT image. The relationship between the high resolution and the light source is studied analytically, four kinds of light source, such as LED, SLD, femtosecond laser and fluorescent light source are described respectively. The choice of light source for OCT system is analyzed in details. The research of this paper is not only the application of laser diode, but also very important in deepen and widen the field of OCT study.

It is shown that post-growth thermal annealing of such a sample with temperature ranging from 800 to 900 °C led to a better confinement of indium rich clusters near InGaN quantum well layers. Transmission electron microcopy (TEM) and energy filter TEM results manifested that the sizes of indium-rich QDs were reduced with increasing annealing temperature. Also, the size homogeneity was improved. Quasi-regular arrays of indium-rich QDs embedded in InGaN quantum wells were observed in the sample of 900 °C annealing. X-ray diffraction also showed the enhancement of InN relative intensity. Photoluminescence measurements revealed blue shifts of photon emission spectral peak, indicating stronger quantum confinement after thermal annealing.

We compared the results of optical characterization between five InGaN/GaN quantum well samples of different well widths. Temperature dependencies of photoluminescence (PL) spectral positions, integrated PL intensities, and PL intensity decay times at PL peaks of all the five samples showed three temperature ranges of different variation trends. The radiative efficiencies of the samples in the high temperature range had the same decay slope, which is supposed to be determined by the defect structures outside clusters. The radiative efficiencies in the medium temperature range varied among samples, indicating different defect structures in the regions between coupled clusters in different samples. Consistent results of temperature dependent variations between the integrated PL intensity and PL decay time among these samples provided clues for reasonable interpretations. Also, we showed the strong dependencies of thermal annealing effects on quantum well (QW) width in InGaN/GaN QW structures. Thermal annealing at 800 °C of a narrow QW width (2 nm) structure led to improved optical quality. However, thermal annealing at the same temperature of a sample of larger QW width (4 nm) resulted in degraded optical quality.

(A1)GaN semiconductors have many important applications in high temperature, high power and high frequency electronic devices such as HEMT and HBT, as well as in blue laser diodes, UV LEDs and detectors. In this work, AIGaN/GaN superlattices have been grown by low-pressure metal-organic vapor phase epitaxy (LP-MOVPE) and characterized by high-resolution X-ray diffraction (HRXRD), atomic force microscopy (AFM), and photoluminescence (PL). The HRXRD measurements show that the crack-free epi-layer grown at optimized condition has very flat interface and good crystal quality. The AFM data also affirmed the HRXRD results with a root-mean-square roughness as low as 0.3 nm. The possible origin has also been proposed for the two peaks observed in the PL spectrum of Mg-doped A1GaN/GaN superlattices.

The InGaN semiconductor materials have important application in visible light-emitting diodes (LED) and short-wavelength laser diodes. In this work we investigate the electronic current overflow and the inhomogeneous hole distribution of the blue InGaN quantum well structures with a LASTIP (abbreviation of LASer Technology Integrated Program) simulation program. The simulation results show that the InGaN quantum well structure has an appreciable electronic current overflow at room temperature. The electronic current overflow problem becomes even more severe at elevated temperatures, which not only affects the emission efficiency of the quantum well structure, but also deteriorates the operation lifetime of the InGaN optical devices. The simulation results indicate that it is possible to improve the electronic current overflow by increasing the doping level of the p-type epi-layers and adding an AlGaN blocking layer in the p-type region. On the other hand, our numerical simulation also shows that, in addition to the electronic current overflow issue, the distribution of the holes in the InGaN active region is very inhomogeneous. It turns out that the laser performance of a single quantum well InGaN laser is better than that of the multiple quantum well lasers. According to our studies, if the barriers between the quantum wells are properly doped, the inhomogeneous hole distribution in the active region may be improved and hence the laser performance of the multiple quantum well InGaN lasers may be enhanced.

A broad area laser diode (BAL) external cavity is experimentally investigated and analyzed using ray transfer matrices. In the experiment, a grating that is placed at the image plane of the output facet of the BAL is used as an external cavity mirror for the slow axis and as a wavelength selective component for the fast axis at the same time. By tilting the grating with respect to the slow and the fast axis direction, respectively, the number of transverse modes oscillating in the cavity can be limited and the spectral line width of the laser diode can be reduced. With this setup, a laser beam with an improved beam quality, an output power of 230 mW and a spectral line width of 0.6 nm (300 GHz) is obtained when operating the BAL at 2.7 times the threshold drive current. We have also investigated a different cavity configuration to achieve alignment insensitivity and stable operation in which the grating was replaced by a flat HR mirror. With a similar beam quality, at the same operation current of the BAL a laser beam with a power of 320 mW and a spectral line width of 1.5 nm (750 GHz) is obtained with this setup.

Using an extra-cavity consisting of an etalon and a mirror, dual-wavelength operation of a high-power broad-area multi-stripe diode laser is achieved. The reflection of the etalon acts as the output of the whole system. The free-running bandwidth of the laser diode is about 2.0 nm. At dual-wavelength operation, the bandwidth of each wavelength component is narrowed to about 0.07 nm, and the space is 1 .65 nm, the same as the FSR of the etalon. We obtain an available dual-wavelength output power of 2.0 W at the drive current of 6.5 A. The power ratio of the components at two different wavelengths can be changed by changing the temperature of the diode laser. To tune the wavelength of the dual-wavelength output, one can changing the temperature of the laser diode and the tilt angle of the etalon simultaneously.

A new rnethod, based on zero point of longitudinal electric field, was used to deterrnine the spatial resolution of electro-optic (EO) probing systern. To examine the spatial resolution of internal and external EO probing systems, an interdigital structure is fabricated on GaAs substrate with and without a layer of Si02 between the electrode and the substrate respectively. Considering Si02 layer or air gap between electrode and EO crystal, the result of electro-optic probing was simulated which is well accorded with experiment. The result indicates that spatial resolution of less than 0.5um and lum are obtained in internal and external EO probing system respectively.

In this study external-cavity laser diodes is analysed from the rate equations approach. Optical power distribution in to the modes is examined as a function of external cavity length and mode number. Also phase variation is analysed in the same way.

Widely tunable gain switching of a grating-coupled surface-emitting laser (GCSEL) has been demonstrated in a simple external cavity configuration for the first time. Pulse duration in range of 40-100ps and wavelength tuning over 100nm have been achieved. High power, tail-free optical pulses have been observed at 980nm.

A rate-equation-based thermal VCSEL model is established, which allows simulation in the non-dc operating regimes, namely, small-signal and transient modulating condition. The model is implemented in conventional SPICE-like circuit simulators, and used to simulate key features ofVCSEL. Making use ofthis equivalent subcircuit representation in the circuit-level EDA design, the authors developed the circuit of VCSEL-based transceiver applied in Gigabit Ethernet.

This paper gives an expression that describes correlation between sinusoidal —modulated signal and average of interference signal in sinusoidal phase-modulated heterodyne interference. The expression can be used for estimating frequency-modulated coefficient of LD(laser diode)and the influence caused by sinusoidal modulation for the intensity of output LD. Experiments are carried out. The correlation is also used for the distance, the displace and the surface profile measurement.

A method of the analysis of spontaneous emission factor have been showed for a planar micro-cavity laser with distributed mirrors based on spectra and half angle at far field full-width half maximum of the lasing mode. After the spontaneous emission radiation patters for a dipole in the micro-cavity is calculated, a considerable value of spontaneous emission factor 0.1 is presented. Then the band filling in the semiconductor and the vacuum field in the micro-cavity are studied together, the spontaneous emission spectrum for a quantum well micro-cavity is described. The maximum scaling of spontaneous emission factor in the practical micro-cavity laser is 3.2*10-3 in the quantum well micro-cavity. The difference spontaneous emission between a dipole micro-cavity with a quantum well micro-cavity is discussed.

A simultaneous generation of multiwavelength optical picosecond pulse trains is demonstrated by the use of multiple-optical-path self-seeding scheme. The external cavity of the Fabry-Perot laser diode consists of three fiber Bragg gratings (FBGs) and a variable optical delay line. The wavelengths of the optical short pulses can be selected conveniently by adjusting the fiber Bragg grating and can be switched simply by just adjusting the optical delay line. The side mode suppression ratio better than 18dB has been achieved when using a 1:99 optical coupler to enhance the seeding power, but the pulse train should be amplified for practical use. The system is simple, easy to operate and of low cost.

The third-derivative saturation absorption spectrum (SAS) of cesium D2 line is demonstrated via the third-harmonic technique by applying the frequency modulation to an external AOM (acousto-optical modulator). By employing the frequency discrimination of the third-derivative SAS, frequency of DBR diode laser at 852nm is locked to the hyperfine component of cesium 6S1/2F = 4 ? 6P3/2F' = 4,5 . Frequency jitter of less than in 10 seconds is estimated based on the error signal after locking in the preliminary stabilization.

In optical telecommunication systems, diode lasers are mostly used either as the signal source in the transmitters or as the energy source in the optical amplifiers, their operations affect the performance of the whole system directly. Only under constant temperatures, diode lasers can perform stably, otherwise, their output wavelengths and power efficiencies will change dramatically.

In this study, semiconductor laser diode is analysed using subcarrier modulation technique. A new approach to intermodulation distortion is obtained with the help of the Volterra Kernels in frequency domain. Computer results are more closer to experimental values elsewhere.

ZnO thin films have been grown on a (400) Si substrate by plasma-molecular beam epitaxy (P-MBE). The sample was characterized by X-ray diffraction (XRD) and photoluminescence (PL). X-ray diffraction result exhibits a strong (002) diffraction peak of ZnO thin film. In PL spectra, a dominant ultraviolet light (UL) emission at 3.265eV is observed at room temperature (RT). According to the energy position of the UL emission, this luminescence at RT was considered to be related to exciton recombination. The samples were annealed in oxygen for two hours at different temperatures, XRD shows the improvement of crystal quality with increasing annealing temperature.

Free space lasercomm technology is one of the key techlonogies for future space base establishments. High power semiconductor lasers are the most promising devices for free space communication. Semiconductor lasers at 800 and 1550nm band are good candidates with small size, low weight and high efficiency. Used as the optical source demans the wavelength suited for atmosphere low loss window super high- power output . narrow beamwidth and high-data-rate. One transmitter approach is to use erbium doped fiber amplifier (EDFA) to amplify the optical signal from a directly modulated 1550 nm DFB laser at 2.5GB/s. Recent progress of the semiconductor laser diodes for free space lasercomm is described in this paper. Studies on the spectrum and the noise of EDFA ,a rough comparision of laser communication schemes at different wavelength bands and key devices . technologies of proposed laser communication in this paper.

Injected-current density and carrier distribution are crucially important factors in Vertical-cavity surface-emitting laser (VCSEL) characteristics, affecting the laser emission wavelength, distribution of transverse-mode, threshold voltage, available output power and operating laser lifetime. Using a method of finding self-consistent solution for the carrier-diffusion and Poisson's equations, of calculating beginning from electrode voltage and of taking into account the whole structure of distributed Bragg reflectors (DBR), we have studied the two-dimensional current density and carrier distribution characteristics of VCSEL. The calculated results show that the injected-current density and carrier distribution determined by the confined-layer depth in VCSEL. The deeper confined-layer in VCSEL is, the more notable current density and carrier distribution are limited in the active region. So the strong confinement benefits to concentrate the current density in the active region to a higher level, at the same time ofthe reduction ofthe threshold.

The thermal characteristics of 1 .3 µ m ridge waveguide InAsP/InGaAsP MQW lasers, including their temperature distribution and thermal resistance, have been simulated by using finite-element methods. The process of three-dimensional model of laser simulation is presented in this paper. The results show that FEM is a useful tool to simulate the thermal conditions of the lasers, which are critical to the design of the laser structure as well as package.

Distributed optical fiber temperature sensor use the principle of temperature effect of spontaneous Raman scattering in fiber and optical domain time reflection (OTDR) to detect the temperature field in space and its changing with time. It can sense the temperature changes along the fiber length by the continuous form of distance in a fiber of several kilometers length. Theoretically, the minimal discernible space length of fiber in the distributed optical fiber temperature sensor system is proportional to the width of incident light pulse, that is, the narrower the width of incident light pulse, the higher the space resolution of fiber. The width, power and edge quality of incident light pulse can directly influence the space and temperature resolution of distributed optical fiber temperature sensing system. This paper focused on the optimum design of light pulse producing based on the use of LD light source. A high power light pulse of narrower width is produced by designing reasonable circuit of increasing voltage, discharging control and making full use of LD, which makes sure to improve the space and temperature resolution of the system.

Space laser communication has attracted closely attention to the improvement in laser technology and communication now. Space laser communication technology is comprehensive and covers many fields. The emitting and receiving of optical signals between satellites and AlT (acquiring, tracking, pointing) of target-signals between satellites or space stations are the crucial techniques in space laser communication. It's necessary to analyze the influencing on the bit error rate from space transmission environment and other factors when discussing some problems in technique scheme of space laser communication. This paper discusses the space laser communication system in which semiconductor laser acts as light source and photoelectric sensor acts as receiver. The chief factors influencing the bit error rate in space laser communication such as the posture of satellite, vibration, the degradation of optical energy, background light and the corresponding solvent are analyzed.

A photonic switching network for parallel multiprocessor cluster system using vertical cavity surface emitting laser (VCSEL) arrays is described. The parallel multiprocessor cluster system provides 64 server nodes interconnected by optical interconnection network with parallel optical links. There are 8 cluster subsystems in the system. Each subsystem includes 8 computers and an optical interconnect backplane of 8x8 crossbar optical interconnection network with VCSEL-based optoelectronic I/O interface. An optical data transmission rate between computers is 5Gb/s which is transmifted by the optical fiber ribbon-based parallel optical data links with 2 channels at data rate of 2.5Gb/s per channel. Every I/O interface between optical interconnection network with each computer includes 16 VCSEL emitter pixels, 16 PIN receiver pixels. VCSEL emitter pixels transformed electrical signals from PCI bus of computer into optical signals, where PIN receiver pixels transformed optical signals from optical interconnect network backplane into electrical signals. The whole optical interconnection network is composed of two level optical interconnect backplanes. A total of 64 computers propagating for data communication of 8 subsystems would be realized.

In this paper, a quasi-three-dimension theoretical model for the Vertical-Cavity Surface-Emitting Laser with oxide-confined layers is showed. The distributions of the equal-potential line, injected current density, carrier concentration and the optical field distribution in the cavity are calculated self-consistently by the finite difference method. The influences of the light output window's radius and oxide-confined layers window's radius are studied. At the same time, we study the influence of the N-type DBR on some characteristics of the VCSEL. The results show that there would be a large difference with practical VCSEL ifthe N-type DBR layers were neglected.

We demonstrate a simple self-seeding scheme for generating dual-wavelength single mode picosecond pulses at a fixed repetition rate with a Fabry-Perot (F-P) laser diode. The F-P laser diode was self-seeded from two fiber gratings that acted as wavelength filters. About 2GHz dual-wavelength pulses with widths of about 45ps and 75ps were achieved when the lengths of external cavities corresponding to different wavelength were equal or different.

Laser Diodes are one of the most important part of fiber-optic communication systems. Therefore proper operating point is always at least a necessary condition to achieve the desired operation. In this study , the intensity modulation is applied to the external cavity laser diode. The chaos with in the system is removed and proper operating condition is achieved by optimizing the external cavity length. The simulation is completely based on time domain approach.

The III-nitride semiconductor materials attract much attention in the past few years owing to their important application in light-emitting diodes and semiconductor lasers. Since the III-nitride semiconductor devices are usually grown on the sapphire substrate, they all have wurtzite crystal structures. The energy bandgaps of the wurtzite III-nitrides are usually obtained experimentally. Several researchers have investigated the energy bandgaps and the bandgap bowing parameters of the wurtzite InGaN, AlGaN, and AlInN alloys; however, the results are quite diverging. In this work we investigate the band structures of the wurtzite InGaN, AlGaN, and AlInN alloys with a CASTEP simulation program. The simulation results suggest that the wurtzite InGaN, AlGaN, and AlInN have a bandgap bowing parameter of 1.21 eV, 0.35 eV, and 3.33 eV respectively. Our simulation results also indicate that the widths of the top valance bands of the wurtzite InGaN and AlGaN alloys decrease when the indium and aluminum compositions increase while the width of the AlInN top valence band has a maximum value of about 6.57 eV when the aluminum composition is near 0.53. In this paper, the investigation of the band structures and bandgap bowing parameters for the zincblende InGaN, AlGaN, and AlInN alloys is also reported.

Radial and longitudinal distribution characteristics of temperature of Nd:YAG laser rod pumped by semiconductor laser line-array are analyzed in this paper. Thermal effect of laser rod, the relation between thermal stress birefringence of laser rod and light pumping power, and the relation between thermolens focal length and pumping power density and repetition frequency of light pumping are studied.

Passive Q-switched operation of a LD-pumped Nd:YVO4 laser is studied with a saturable absorber GaAs as a passive Q-switched component and F-P output coupler. Q-switched pulses with pulse duration 47ns, pulse repetition rate 1183 kHz, pulse average power 430mW and beam quality M2=1.13 in a TEM00 mode were produced with Q-switched pumping threshold 1700mw. We performed numerical calculations of coupled wave equations for case of GaAs playing the role as mentioned above, discussing passive Q-switched mechanism and the dependency ofpulse duration and pulse repetition rate on pumping rate, which was well in agreement with the experiments' results. A brief and effective technique for compact Q-switched solid-state laser having multiple functions is provided.

In this paper, the driving equation about chaotic controlling in injected semiconductor lasers has been presented with periodic driving modulation, which is beaten oscillation. Under suitable modulation depths and frequencies, we can effectively control the lasing chaos into stable periodic orbits (limit cycles) and convert the lasing chaotic oscillations frequencies onto the modulation frequencies. It is found that the transient driving response to chaotic oscillations can be all very fast with different modulation driving frequencies.

In this letter we introduce three typical cw, singly resonant OPO configurations based on PPLN and the different advantages and disadvantages of them. And we also show three different kinds of PPLN's and describe the differences between them.

The Linewidth enhancement factor (Alpha factor) is a key parameter in optical system design in terms of both continuous wave operation and hight frequency modulation conditions. Since the linewidth is reduced in external cavity configuration by weak optical feedback, the role of Alpha factor is simulated in such a condition. Both the values of Alpha and feedback parameters are optimized in such a system.

In this work, we report the thermal diffusivity of r.f plasma polymerized o-toluidine thin film using the Photothermal probe beam deflection technique. The measurements are carried out in two different coupling media namely carbon tetra chloride and liquid paraffin. The deflection signal is analysed using the Phase method and has obtained consistent results for the two different environments.

In Dense Wavelength Division Multiplexing (DWDM) fiber communication system, more and more channels have to be put into a single fiber in order to fulfil the ever-increasing demand for high capacity. This put strict requirements on the wavelength characteristics of various active and passive optical components. Generally speaking, in current DWDM system, a wavelength accuracy of 5pm is necessary for analyzing channel performance, and 0.5 pm is required for the aging test of components. An extended cavity laser diode (ECLD) frequency stabilized to saturated absorption lines of acetylene C2H2 with a potential long term frequency stability of 10-12 can provide excellent wavelength reference for DWDM communication system[1][2][3]. In this paper, we describe a practical 1.5µm wavelength transfer standard based on C2H2 stabilized DFB laser and tunable fiber Fabry-Perot etalon[4]. This transfer standard is suitable for the calibration of widely used optical spectrum analyzers (OSA) and wavelength/multi-wavelengths meters. This device is currently under development in the Quantum Division ofNational Institute of Metrology (NIM).

Vibration of the interferometer signal is amplified and fed back to the laser diode after photo-electronic conversion, which controls the injection current of the laser diode. By using the character that the output frequency of the laser diode changes linearly with the injection current, the output frequency can be modulated by the injection current. Through this, phase vibration is compensated and interference pattern is stabilized. This paper describes the formula of the stability. The stabilization factor is measured and the main factors that affect the stability is described. These can supply references to the adjustment of the interferometer, the feedback module and the stability of the interferometer.

The ultraviolet light emission from diamond films was investigated. The diamond films on Si (100) were deposited by microwave plasma chemical vapor deposition. The B-doped and P-doped layers were formed by cold ion implantation. The properties of p-type and n-type layers were characterized by SEM, SIMS, Raman spectroscopy and Hall measurements. The experimental results showed that a sharp emission peak at 235nm was observed at 22V for 9niA at room temperature. A broad A-band emission in the visible region was also appeared simultaneously. The intensity of ultraviolet emission was changed with carrier mobility and temperature. The results obtained have discussed in detail.

The mini pulse laser rangefmder (LRF) uses semiconductor laser as its source. This kind of LRF has property of safe, small size and low cost. It can be applied in sports and some filed of engineering just like wire layout. To extend its application field, the measurement parameter, which is now 1km in maximum range and 1m in accuracy at one measurement, need to be improved. The raise time of pulse can be more sharp, the speed response of receiver can be more quickly and the efficient arithmetic should be taken.

After semiconductor laser irradiation on dry seeds of peanut with 0.25w/cm2 X 300s, 480s, at 650nm ,the effects of ultrastructures of plumule cell and chromosomal aberration have been studied in the present paper. The results showed many aberration types, such as earlier separated mitosis metaphase, variability of number, sticky, chromosomal laggards and ioop and so on were found in treatment group. With H-600 transmission electron microscope, the effects of ultrastructures of plumule cell were observed. There were difference in the cell on membrane system, fatbody and nucleus, especially in proteinbody. In this experiment, the sprout of peanut seeds( irradiated by semiconductor laser 0.25w/cm2x300s, 480s, 650nm) and generation agro-character also have been researched.

A novel, practical, eye-safe solid state laser is described in this paper. Using adjustfree solid state laser with heat conductive cooling element, Ce-Nd:YAG materials, directional prism resonator and Cr4+:YAG passive Q-switch as the pump source for OPO, and with overlapped self-collimation structure, laser energy of 10.5mj, wavelength of 1.57 µ m, pulse width of about 6.3ns and beam divergence of 5mrad were obtained. Also, optical axes was steady under the condition that laser was operated for 30~60 seconds at 5Hz repetition rate.

Advances in Diamond Anvil Cell (DAC) technique have enabled a variety of condensed matter physics studies to be performed at very high pressure, up to -56O GPa. Valuable information on phase stability, EOS, band structure and metal to insulator transition has been obtained on a large number of semiconductors. The introduction of the laserheating technique has opened up a new era in high-pressure, high-temperature research, for experiments that were previously possible only through shock wave techniques. This technique is presently being exploited to synthesize novel materials hitherto only theoretically predicted. The search for metallic hydrogen is still on, and DAC experiments under low temperature and high pressure have been performed to draw the phase diagram of hydrogen. A question that is paramount in every mind concerns the ultimate structure of condensed matter [1,2]. Many elemental systems appear to adopt the body-centered cubic phase. Further many elemental insulators and semiconductors turn metallic at high pressures. Very recently sulfur has been shown to become metallic and superconducting near 93 GPa [3]. This suggests that elements such as Br, Cl may turn metallic at pressures reachable today with the diamond anvil cell. Improvements in DAC capability (up to ~56O GPa), the fabrication of micro X-ray beams (~3 µm), coupling the DAC with the SRS (brilliance ~1015 photons/s/mrad/100mA/0.1%??/?), the possibility of laser heating (~7000 K) simultaneously with pressure, and the advances in area detectors such as the imaging plate system and charged-coupled devices open up new areas for semiconductor physics research that need to be judiciously exploited. For DAC electrical resistivity work, a tough problem has been in attaching good ohmic contacts to the sample. The mechanical contacts often used for performing measurements on bulk would severely degrade the device properties of the heterostructure. Until advancement occurs in this area, the information obtained through electrical resistivity, Hall mobility, and thermoelectric power cannot be added to the probeless measurements.