We report on the investigation of the long term stability study of InAs1-xSbx (x=0.09) high operation temperature (HOT) photodiode grown on GaAs substrate. The electrochemical passivation technique was proposed to modify the mesa sidewalls properties and obtain anodic sulphur coating covered by SU-8 negative photoresist. The dark current densities of sulphur anodic film, SU-8 photoresist and unpassivated devices was compared. Obtained results indicates that the surface leakage current was not fully supressed by unipolar electron barrier. The most stable behaviour after an exposure of 6 months to atmosphere and annealing at 373 K for 72 h was observed for sulphur anodic passivation. This technique turned to be effective also in reduction of oxygen (O) 2s peak in X-ray photoelectron spectroscopy (XPS) in comparison with only etched sample.
An important issue in security systems is that of selection of the appropriate detectors or sensors, whose sensitivity guarantees functional reliability whilst avoiding false alarms. Modern technology enables the optimization of sensor systems, tailored to specific risk factors. In optical security systems, one of the safety parameters considered is the spectral range in which the excitation signal is associated with a risk factor. Advanced safety systems should be designed taking into consideration the possible occurrence of, often multiple, complex risk factors, which can be identified individually. The hazards of concern in this work are chemical warfare agents and toxic industrial compounds present in the forms of gases and aerosols. The proposed sensor solution is a hybrid optical system consisting of a multi-spectral structure of photonic crystals associated with a MEMS (Micro Electro-Mechanical System) resonator. The crystallographic structures of carbon present in graphene rings and graphenecarbon nanotube nanocomposites have properties which make them desirable for use in detectors. The advantage of this system is a multi-spectral sensitivity at the same time as narrow-band selectivity for the identification of risk factors. It is possible to design a system optimized for detecting specified types of risk factor from very complex signals.
Gradient structures are very important for sensors, laser and wave-guide techniques, telecommunications and other
techniques which employ radiation propagation and conversion. By varying admixture concentration, the stress occurring
in the structure may increase or reduce, which is vital for charge carrier movement velocity. We discusse two kind of
gradient structures of thin TiNx layer with a total thickness of approximately 22 nm deposited on the Si(100) substrate
and multi-layer structures with a Si-Pd and Si-Mg bi-layer periods. The gradient structures were deposited using a laser
ablation of target-compound materials. A Lambda Physics excimer laser (model LPX 305i; t ~ 15 ns, λ = 193 nm) with
f = 5 Hz operating frequency was used for layer depositing. The analyses confirmed the presence of the gradient
distribution of deposited materials. The gradient structures proved highly sensitive to both thermal effects and strong
adsorption of ambient gases. The usefulness of titanium-containing structures for gas, especially hydrogen and oxygen,
sensors was confirmed. Due to the strong gas adsorption, the gradient structures used in radiation conversion or waveguide
technology should be adequately protected against ambient conditions.
The optical methods to determine refractive index profile of layered materials are commonly used with spectroscopic ellipsometry or transmittance/reflectance spectrometry. Measurements of spectral reflection and transmission usually permit to characterize optical materials and determine their refractive index. However, it is possible to characterize of samples with dopants, impurities as well as defects using optical methods.
Microstructures of a hydrogenated crystalline Si wafer and a layer of SiO2 - ZrO2 composition are investigated. The first sample is a Si(001):H Czochralski grown single crystalline wafer with 50 nm thick surface Si02 layer. Hydrogen dose implantation (D ≤ 4x10l6 cm-2) results in a creation of porous (spongy) -like buried Si layer. Interaction between hydrogen atoms and a semiconductor, involving adsorption, surface diffusion, and desorption, continue to be an important issue in microelectronic device and sensor fabrication. Hydrogen-implanted silicon (Si: H) has become a topic of remarkable interest, mostly because of the potential of implantation-induced platelets and micro-cavities for the creation of gettering -active areas and for Si layer splitting. Oxygen precipitation and atmospheric impurity are analysed.
The second sample is the layer of co-evaporated SiO2 and ZrO2 materials using simultaneously two electron beam guns in reactive evaporation methods. The composition structure was investigated by X-Ray photoelectron spectroscopy (XPS), and spectroscopic ellipsometry methods. A non-uniformity and composition of layer are analysed using average density method.
Ti-Si material compositions with layered structures are very interesting for sensors and optoelectronics applications. The ultra-thin multilayered Ti/Si films were prepared by pulsed excimer laser ablation (PLA) at wavelength of 193 nm from the Ti and Si targets. Two samples S1 and S2 with multilayered structures of four bilayer period of ~20 nm and five bilayer period of ~1 nm thickness of the Ti-Si layers on Si(100) substrates, respectively were deposited. Samples were post-deposition heated at 600°C in argon atmosphere for 10 min by rapid thermal process (RTP). The composition structures were investigated by transmission electron microscopy (TEM), secondary ion mass spectrometry (SIMS), grazing X-Ray reflectance (XRR), and X-ray diffraction (XRD) methods. The results show that intermixing of the Ti- and Si-based films appears even in the as deposited layers. The multilayered structure of the S2 sample after post-deposition annealing indicates the formation of the titanium silicide layer. The domination of interfacial and surface energies leads to the formation of metastable phase with a low interfacial energy.
Thin films of Zr-silicate were deposited on silicon and BK7 glass substrates by EB co-evaporation. The mixing thermodynamics of the ZrO2 - SiO2 system was analysed. Chemical bonding in Zr-silicates has been studied by X-ray photoelectron spectroscopy. The structural and optical properties and the surface morphology were investigated.
The transport of light through the different materials media is a rich and fascinating topic of research. The problems of the light transmission theory and the Law of Light Transmittance were presented in . This theory is universal for all electromagnetic ranges. The Ewald-Oseen extinction theorem corresponds to the Law of Light Transmittance, which was shown. Here we discuss several aspects of light transport omitted in article  as wave packets, scattering, a local periodicity, and electromagnetically induced transparency.
The investigation results of wideband (8-12 μm) antireflection coatings on germanium substrate and spectral characteristics of interference wideband filter for spectral range of 8-12 μm are presented. For design of filters and antireflection coatings the following layer materials were used: Ge, ZnS and Mira, and substrate materials such as: Ge for antireflection coatings and ZnSe for interference filters. Wideband filter for the range of 8-12 μm requires application of additional two filters cutting off radiation from the range of 1-7 μm. The cutting off filters are interference filters for which construction germanium, Mira, and ZnS were used. The constructions of basic and cutting off filters were designed considering technical possibilities of vacuum device BAK 550 of the Balzers firm.
Thin films of zirconia were deposited on quartz substrates by conventional reactive electron beam deposition and ion-assisted deposition. The influence of the post-deposition annealing between 400°C and 900°C on the structural and optical properties and on the surface morpohology was investigated. It is shown that after post-deposition annealing the ZrO2 films the degree of order becomes higher. The contribution of the monoclinic phase increases with the rise of annealing temperature. The post-deposition annealed (temperature range: 700-900°C) samples exhibit lower threshold to damage for the radiation of pulse Nd:YAG laser. Correlation between the observed film properties and laser damage threshold is discussed.
We have analyzed the basic examples of cases of completely transmitted light. The text presents a theory of light transmission through material media. This theory is universal for all electromagnetic ranges. The Law of Light Transmittance is proposed. Moreover, the Ewald-Oseen extinction theorem corresponds to the Law of Light Transmittance, which is shown.
Microstructure and laser damage resistance of dielectric optical thin-film coatings was determined by several experimental techniques. These are film growth and test parameters as well as thin-film characteristics, e.g. absorption, structure and reflective index. The oxide coatings (HfO2, Nb2O5, Ta2O5, TiO2, and ZrO2) were prepared with varying technology parameters by reactive e-beam evaporation in Leybold A1100 batch coater. The structure of the films was found to be amorphous for very thin films with tendency to columnar growth for thicker films. X-ray diffraction (XRD) and reflectivity (GIXR) were used to determine the structural properties of the films. The surface morphology of oxide layers was determined using atomic force microscopy (AFM). The optical properties were investigated in UV-IR ranges by spectrophotometer measurements. The changes in the shape of absorption edge are found to be related to the structure of thin films. Laser damage threshold for the coatings was measured at wavelength of pulsed Nd:YAG laser. Correlation between the observed film properties and laser damage threshold is discussed.
The subject of modern and save sunglasses is entertaining to many people especially due to anti-UV eye protection. Many people use glasses with anti-UV or blue-block coatings to driving or sun-tanning. There were analyzed transmittance and reflectance of different sunglasses made with thin-layer coatings. Sunglasses with absorption-interference protection are specially interesting due to technical simplicity of production.
The narrow-pass-band polarization filters are mentioned. Several methods are used for such type of filters. The construction of narrow-band interference polarization filters with liquid crystal space (LC) layer has been presented. The peak of transmittance has been designed at wavelength 1064 nm. Refractive index of liquid crystal changes with driving voltage. At optical thickness of space layer changed to the multiple of quarter-wave thickness the construction has a stop-band in interested spectral range.
There are presented special laser mirrors exhibiting high reflectivity and negative group delay dispersion over broad frequency range. These dielectric laser mirrors are enabled to compression of the generated radiation and offer a general solution for broadband feedback and dispersion control in femtosecond laser systems. Such mirrors would been used to OPO systems, to chirped pulse amplification systems and pulse compressors.
Classical narrow-band interference dielectric filters with all-dielectric reflectors have the quarter-wave stacks separated by a half-wave thickness spacer layer. These filters are essentially the Fabry-Perot filters and hence the theory developed for the latter applies in full. The paper present the theory of narrow-band interference dielectric filters with non-conventional spacer layers. This spacer consists of the layers of two different materials. The optical features of these filters are compare with the features of Fabry-Perot filters. It is analyzed the influence of the errors of layer on spectral characteristics. Presented theory may be applied to any spectral ranges as well as to any thin film materials including absorbing and nonlinear materials.
The Fabry-Perot interferometer (FPI) is conceptually a very simple structure and, in principle, a lossless device when on resonance. Hence the FPI is a versatile and flexible component and a prime candidate for use as a narrowband spectral filter in wavelength division multiplexing systems with channel spacing of the order of nanometers. The FPI with single mode coupled fibers and liquid-crystal filter have high finesse and easy selectively changed wavelength of peak. To effect demultiplexing one of the transmission peaks is tuned to the wavelength of the required channel.
The paper presents the conception of narrow-band interference filters with variable half-width at normal incidence. Such filters are a combination of a birefringence layers and dielectric multilayers. These interference filters need linear polarized radiation. The effective optical thickness of separating layer changes value when the filter is rotated at normal incidence. These filters may be useful as a switching element, in detecting and telecommunication systems.
The subject of modern, save and stylish eyewear is entertaining not only to people with unwell eyesight. Many people use glasses with anti-UV or blue-block coatings, glasses for driving or working with a computer. There were investigated the blue-block eyewear. There were analyzed reflected radiation at 300 - 400 nm wavelengths with cross- incidence. The traditional eyewear with classical or stylish frame may not protect sight against the UV radiation.
The matter of the analysis are coated plane-parallel plates of BK7 glass and Nd:YAG microchip lasers illuminated with coherent beam. Short wave and long wave absorption bands and dispersion of refractive index of glass have been omitted to simplify the problem. There are analyzed multilayers designed for visible or IR range. Analyzed examples can be easily generalized to other substrates, layers' materials and wavelength.
Narrow-band polarizing interference filters make the new category of thin layers construction. Due to the compact trends the narrow-band polarizing interference filters eliminate one of two elements used traditionally on separate substrates: narrow-band filter and thin layer polarizer. Considering them as narrow-band interference filters it is possible to project their parameters such as center wavelength or the half bandwidth. The choice of the narrow- band polarizing interference filters design is controlled by the polarizing degree.
There are used many different sources of radiation in present optic systems. The paper presents the beam splitters of radiation at a three different diode lasers used to one optical path. There were analyzed wavelengths: 670, 830, and 904 nm at 45 degrees angle of incidence.
As a result of investigation of construction and technology of anti-laser filters based on colored glass and interference thin-film coating, the new solutions of absorption- interference filters have been developed. Their main advantages are: very high and selective absorption, even for several wavelengths (simultaneously) with increased transmission in the visible region, and increased energy resistance for high power laser systems.
One of the latest laser beam applications is to selectively pump energy and generate coherent radiation transferred to another wavelength. It expands because the amount of generating sources with different selective wavelength permanently grows. Especially it applies to laser diode pumped systems resulting with highly efficient all solid-state compact lasers. These systems require well fitted thin layers' coatings. For microchip lasers as well as for parametric generators, the project of thin-layers stacks needs wide spectral analysis. Thin layer coatings for compact lasers have been elaborated. Stacks were based on oxide layer and were made with classical electron beam equipment.
This paper presents two concepts of the design of antireflection coatings for wide-angle windows for selected wavelength. The first one is the simple application of corrected wide-band antireflection coatings designed at a normal incidence. The second is stack optimized at large angle of incidence. The design is made at 0 degrees-65 degrees range of angles of incidence.
The paper presents the design of nonpolarizing beam- splitters inside a glass cube, which bases on quarter-wave layers at (lambda) 0 equals 632.8 nm and 45 degrees incidence angle. This example shows the design for achieving a 50 percent reflectance and 50 percent transmittance at (lambda) 0 for both polarization states.
The article presents the thin-film stack systems creating the new type of optical elements. The said element substitutes a thin-film plane polarizer and narrow-band interference filter simultaneously for selected wavelength. The comparative analysis of the new construction basic parameters was carried out in the function of beam incidence angle on the system with changes of analogical values for classical narrow-band filter. The narrow-band polarization interference filters for (lambda) equals 1064 nm have been designed and made with application of classical vacuum plant with electron guns.
Graded-reflectance mirrors for Nd:YAG laser have been made and tested in the laser resonator. The output energetic characteristics and the results of laser beam divergence measurements are presented for the different GRM mirrors. The output energy ca 10% smaller then for classical uniform-reflectance mirrors were obtained, but the beam divergence were reduced more by half.
There are presented some solutions of anti-laser absorption-interference filters, satisfying the demands of high transmission in the visible range, enlarged resistance and improved work comfort at longer usage. In order to increase the total transmission is was used the anti- reflecting coatings onto the glass surface. Besides the contrast increase the work comfort is improved. The anti-reflecting layers are necessary in case of using the large power lasers due to the possibility of reflection of large intensity radiation from the filter surface. A selective reflection of light by thin-layer interference pile was used in construction of anti-laser filters for several wavelengths. The absorption-interference filter was elaborated for I and II YAG:Nd laser harmonics. By depositing the CUT-OFF type thin-layer filter onto the infrared and NIR filters, virtually brightened image, high rising of contrast and the final green color well accepted by eye were obtained.
The paper presents Fabry-Perot type interference metallic filters with double separator layers, which enables good visibility and blocks thermal radiation. Elimination of UV radiation below 320 nm is obtained by glass substratum. The UV radiation interlocking up to 400 nm can be achieved by an additional interference coating.
In this paper some solutions of anti-laser absorption-interference filters are presented, satisfying demands of increased transmission in the visible range, enlarged resistance, and improved work comfort at longer usage. In order to increase the total transmission the anti- reflecting coatings were used on the glass surface. Besides the contrast increase the work comfort is improved. The anti-reflecting layers are necessary in case of using the large power lasers due to the possibility of reflection of large intensity radiation from the filter surface. A selective reflection of light by thin-layer interference pile was used in construction of anti-laser filters for several wavelengths. The absorption-interference filter was elaborated for I and II YAG:Nd laser harmonics. By depositing the cut-off type thin-layer filter onto the infrared and NIR filters virtually brightened image, very apparent rising of contrast, and a final green color well accepted by the eye were obtained.