Proceedings Volume 10830

13th Conference on Integrated Optics: Sensors, Sensing Structures, and Methods

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Proceedings Volume 10830

13th Conference on Integrated Optics: Sensors, Sensing Structures, and Methods

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Volume Details

Date Published: 23 August 2018
Contents: 2 Sessions, 37 Papers, 0 Presentations
Conference: Thirteenth Integrated Optics: Sensors, Sensing Structures and Methods Conference 2018
Volume Number: 10830

Table of Contents

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Table of Contents

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  • Front Matter: Volume 10830
  • 13th Conference on Integrated Optics: Sensors, Sensing Structures and Methods
Front Matter: Volume 10830
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Front Matter: Volume 10830
This PDF file contains the front matter associated with SPIE Proceedings Volume 10830, including the Title Page, Copyright information, Table of Contents, and Conference Committee listing.
13th Conference on Integrated Optics: Sensors, Sensing Structures and Methods
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Numerical modelling of pulse formation in Er3+-doped Q-switched fluoride glass fiber lasers
We perform a numerical analysis pulse formation in Q-switched fluoride glass fiber lasers. For this purpose we apply a method of lines to convert partial differential equation into a set of ordinary differential equations at a set of selected sampling points along the longitudinal axis. The results show the dependence of the signal pulse shape and pulse delay, generated at 2850 nm, on the pump power and fiber length.
Signal correlation methods for photodetector noise characterization
M. Chojnowska, K. Achtenberg, J. Mikołajczyk
Noise parameters of a photodetector have a significant role in many science and life activities, e.g. gas spectroscopy, optical communication, objects detection and recognition, construction of laser rangefinders. However, applied noise measurement methods are not so efficient to study new generation of infrared radiation detectors. The paper presents performance comparison of two correlation methods of photodetector signal to determine its noise. These methods apply the signal correlation of a time series with itself (autocorrelation method - ACM) and the similarity between two time series (cross-correlation method with two-channel signal readout - CCM). Both methods were analyzed using a designed simulator (MATLAB/Simulink). It makes it possible to design a special system consisted of electronic block of a twochannel signal readout and signal processing unit. The verification of this setup performances for noise measurement was performed using some low-noise resistors with well-defined resistances. Finally, the setup was also used to measure noise spectral density of MCT detector.
Numerical analysis of integrated optics structures based on wide band gap semiconductor materials for biosensors application
The paper presents numerical analysis of integrated optics structure in the form of planar waveguide based on wide band gap oxide semiconductor material. The theoretical analysis of planar waveguide structure was focused on determination of waveguide properties - effective refractive index as a function of waveguide layer thickness for two type of applied waveguide materials – titanium dioxide TiO2 or zinc oxide ZnO and with cover layer based on biological liquid modeled as a saline solution – sodium chloride. The theoretical analysis was carried out for three type of substrate materials: BK7 glass, quartz and sapphire. The second step of research was focused on analysis of homogenous sensitivity dNeff/dnac, finally modal field distribution in planar waveguide structure was also presented.
Face re-identification across pose in thermal infrared spectrum based on local texture descriptors
Face re-identification is a challenging task which is aimed to check similarity of two faces shown in the images. Face recognition system have been investigated since many years mostly in visible domain. We investigate face recognition methods based on facial images acquired in far-infrared range (thermal spectrum). The main reason for using thermal infrared for face recognition is to observe people in night conditions. However, this task is not free of challenges. In this paper we investigate the impact of various head positions on efficiency of face re-identification. The paper presents our measurement approach, results of many series of tests as well as performance metrics of re-identification based on three state-of-the-art facial descriptors.
Optimizing the light source design for a sensor to measure the stroke volume of the artificial heart
The article presents the results of optimizing an illuminator structure, which is an integral part of the optical sensor, for determining the stroke volume and cardiac output of the extracorporeal pulsating heart prosthesis supporting the operation of the myocardium. The obtained results of the optimization were verified experimentally. The tests were carried out for various light sources. The following were taken into account: low and high-current LED diodes operating in the visible band, LED diodes operating in the near-infrared range and fiber optics. In addition to the results of the study, the paper presents problems arising during the use of particular types of illuminators and proposed ways to overcome them.
Studying the influence of markers arrangement on accuracy of the membrane shape mapping in the new DFD method
The Depth from Defocus (DFD) type method was developed for visual distance measurement. It was used to determine the shape of the flaccid membrane of the extracorporeal pneumatic heart assist pump. In the previous conference paper the technique of accuracy measurement of membrane shape mapping of an artificial ventricle was presented. The study was conducted on three membrane shapes which are well mathematically described: convex, concave and flat. For all cases the rigid membrane models were designed and 3D printed. The next study focused on extending the invented technique to other models of membrane with the well-known math formulas. Two new irregularly shaped models were produced and tested. Analysis of the obtained results during the rigid membrane models tests revealed the significant effect of the markers arrangement on the membrane shape mapping accuracy. Therefore, another arrangement of markers was tested. In the paper the comparison of the results obtained for the different arrangements of markers was presented.
Vision sensor for a filament positioning in the optical fiber tapering system
Tapered optical fibers are created by stretching of the optical fiber so that their diameter at the narrowest area is only few microns. In this form, they are very interesting for optical sensor applications. The developed vision sensor for a filament positioning is a key element of the optical fiber tapering system. It allows controlling the speed of stretching the fiber what significantly reduces the chance of its breaking. The paper presents the sensor developed based on a fixed-focus camera equipped with a wide-angle lens and using image processing and analysis techniques. Determining the position of a filament consists in determining the angle of its deviation from the reference position. The required stretching speed of the fiber is determined based on the determined angle. In the paper, the way of carrying out measurements of position of optical fiber using the sensor and the results obtained were presented.
Thermal and optical study of the new methacrylic copolymers useful in POF technology
B. Podkościelna, K. Fila, M. Goliszek, et al.
This study the copolymerization and physico-chemical properties of the new copolymers of meth/acrylic esters: butyl acrylate (AB), ethylhexyl acrylate (AEH), or methyl methacrylate (MMA) with 2,2,2-trifluoroethyl methacrylate (TFEMA) used as a dopant are presented. Chemical structures of the copolymers were confirmed by attenuated total reflection–Fourier transform infrared (ATR/FT-IR) spectroscopy. Thermal properties of the synthesized materials were investigated by means DSC (Differential Scanning Calorimetry) and TG/DTG analyses. The influence of fluorinated dopant on the thermal and optical properties of the copolymers were evaluated in detail.
Synthesis and characterization of polymeric blends based on polysulfone for special applications
In this paper, synthesis and characterization of new polymeric blends are presented. For copolymerization, the following components: N-vinyl-2-pyrrolidone (NVP), bisphenol A polysulfone (PSU) and bisphenol A glycerolate diacrylate (BPA-A) were used. 2,2-dimethoxy-2-phenyloacetophenone was applied as a photoinitiator. In this method, five polymeric blends with different amounts of PSU were synthesized. Their hardness was investigated using the Shore method. The effect of polysulfone amount on their mechanical and thermal properties was analyzing by means of attenuated total reflectance Fourier-transform infrared spectroscopy (ATR/FT-IR) as well as thermogravimetry and differential thermogravimetry (TG/DTG)
Manipulation of virtual 3D objects with the use of graphic tags and AR technologies
Marek Piszczek, Mateusz Pomianek, Marcin Maciejewski
In the real world, we can easily manipulate small objects that we hold in our hands. We can see them carefully from each side, look at the details by bringing them close to the eyes, etc. and what if the object has microscopic dimensions or on the contrary - it is very large. In this case, the matter is not so simple. However, if we have digital models of such objects, the above problems can be solved with the use of virtual technologies. An interesting example may be the use of augmented reality for this purpose and graphic tags that act as triggers for the visualization process. The tags mentioned above also play the role of positioning and orientation system of the spatial configuration: a virtual object - an observer. The process of determining spatial parameters is initiated by the results of image processing and analysis. Tests of such a solution were carried out using the optical see-through display. Initial positioning and orientation of the object relative to the observer is carried out by analyzing the video stream coming from the integrated camera. Tests of such a solution were carried out using the optical see-through display. Initial positioning and orientation of the object relative to the observer is carried out by analyzing the video stream coming from the integrated camera. The extended scope of object manipulation (change of position, orientation and scale) is obtained by means of a GUI interface integrated with the display
Virtualization of the measurement system for the MIMO THz scanner
Marek Piszczek, Mateusz Pomianek, Marcin Maciejewski, et al.
The development of the final form of the THz scanner in MIMO technology (Multiple Input Multiple Output) requires the preparation of a measuring station that integrates control and measurement, vision and mechanical systems. The management of such a measurement system can be improved by using elements of virtual technologies. Spatial analyzes concerning a measurement object can be made using measurement space virtualization based on data from a ToF (Time of Flight) camera. Collision-free operation of the XY type scanner and Robot arm can be verified in virtual space. The correct operation of the measurement system can be verified using the augmented reality technology. The abovementioned elements very well fit into the idea of the so-called Industry 4.0 in which we are talking about cyber-physical systems. For the purposes of the research project being carried out, a simplified model of operation of such a system was proposed. However, the main focus was on the possibility of using virtual technologies and the benefits of using them.
Testing the SteamVR trackers operation correctness with the OptiTrack system
Marcin Maciejewski, Marek Piszczek, Mateusz Pomianek
SteamVR technology has become very popular in virtual reality applications. The most common example of its use are the HTC VIVE controllers. Applications, however, are not limited to controllers held directly in the hands. SteamVR trackers can also be placed on real objects that have their representation in the virtual world. Due to the specificity of use, it is necessary to choose the optimal part of the object to which the tracker will be attached. However, it is not always possible to obtain satisfactory results with this method. An alternative solution is a dedicated tracker project sometimes with an original detector constellation. Regardless of which path the trackers and VR applications designers will follow, it is indispensable to be able to verify the correct operation of the system: object and associated tracker, in laboratory conditions. The experimental measuring stand and the testing method has been developed based on the OptiTrack motion tracking system. The initial positive results of such measurement stand were obtained. The tests carried out concerned both the production models and the own design tracker construction placed on various shapes test objects.
Study of physico-chemical properties of the new potential optical polymers based on 2-hydroxyethyl methacrylate
In this work synthesis, optymalization and study of physico-chemical properties of the new functionalized copolymers are presented. 2-Hydroxyethyl methacrylate (HEMA) and 2,4-dichlorophenyl methacrylate (2,4ClPh-M) copolymers have been prepared by bulk polymerisation. As a polymerization initiator (α,α’-azoiso-bis-butyronitrile) was used. A different weight ratio of HEMA to 2,4ClPh-M was applied. In this way 10 different copolymers were obtained. The structure of new materials was confirmed by spectroscopic methods (ATR-FTIR). The thermal stability of the obtained copolymers were studied by thermogravimetric analysis (TG/DTG).
Optical properties of monomer-doped liquid crystalline materials for waveguiding structures
Katarzyna A. Rutkowska, Miłosz S. Chychłowski, Bartłomiej Turowski, et al.
Experimental results on determination of optical parameters of monomer-doped liquid crystalline materials are presented. Refractive indices, as well as propagation losses, have been particularly determined as a function of the monomer concentration. Materials characterized in this way can be applied for fabrication of waveguiding structures with use of the photo-polymerization process. Several factors, such as composition of the LC-monomer mixture and UV illumination conditions, are needed to be taken under consideration when fabricating structures of satisfactory quality. Importantly, their optical properties may be additionally tuned after fabrication what is in a huge advantage when compared to waveguiding structures manufactured in other materials.
Mobile border verification of travellers based on fingerprints: experimental studies
The paper describes the results of experimental research on the mobile verification of travellers based on fingerprints. Three-day tests were carried out at the border crossing in Terespol, Poland. The developed system automatically acquires personal and biometric data (fingerprints) from the Polish biometric passport, determines their quality and compares with the live data collected from the traveller. In addition, the system measures the time of individual stages of the process and determines total transaction time. For total number of correctly scanned travellers equal to 128, false acceptance rate equals to 0, while rejection rate is less than 1%. The average transition time of border check was 37 seconds.
Microbending losses in optical fibers with different cross-sections
G. Wójcik, K. Poturaj, P. Mergo
We fabricated three silica glass preforms with different cross-sections, which were used to draw optical fibers. A classic preform had a circular shape and was prepared on the MCVD machine, second preform with a circular outer shape and hexagonal core was fabricated by the hybrid method, last preform with hexagonal core and outer shape and was fabricated by stacking method. Each preform were used to draw series of fibers with parameters corresponding to the geometry of typical telecommunication fibers. In following part of our experiment all fibers were used in microbending tests.
The universe is not electrically neutral (Withdrawal Notice)
Publisher’s Note: This paper, originally published on 14 August 2018, has been withdrawn by the publisher for editorial reasons.
Investigation of optical fiber current sensor with external conversion in unstable stands
In this work are presented possibilities of using optical fiber current sensors with external conversion in power protection (PP) of high power protection system. From the standpoint of the PP the most important is that the secondary signal (from the current transformer) is accurately reflecting the primary signal (current). Quality of this process is characterized by signal parameters such as: shape, amplitude, phase, number of transformed harmonics of the signal. The tests were performed on a measuring setup allowing simulation of real conditions using an air magnetic coil. Results of tests proved very good dynamic properties of the sensor allowing its application as an element of a power protection system.
Optical fiber current sensor with external conversion in high voltage environment
Kamil Barczak, Dominik Duda, Krzysztof Mazniewski
The presented work is concentrated on investigation of electric properties of optical fiber current sensor with external conversion [1]. The sensor was examined in the presence of high voltage (up to 30 kV). Moreover, one high voltage trial at 70 kV was carried out for 1 min. [2]. High voltage tests showed very good insulating properties of the sensor. A leakage current was estimated. Its value was lower than in the case of high-voltage ceramic insulator (Fig. 1 and Fig. 2). Presented results allowed to run a high-voltage test of the sensor connected to a light source and a photodetector which were powered-on. The test was successful, which proves very good isolation properties of the presented sensor.
Investigation of physical properties of ZnO semiconductor material for biocompatible coating layer applications
Przemyslaw Struk, Michal A. Borysiewicz
The paper presents investigation of physical properties of ZnO semiconductor for biomedical applications as a coating layer for example in medical devices and structures. The research was focused on determination of surface topography by SEM method, surface roughness by AFM method, chemical composition by EDS method and crystalline structure of ZnO by Raman spectroscopy. The investigated ZnO coating was deposited by reactive magnetron sputtering on quartz substrate.
Optimizing arrangement of markers on a flaccid membrane surface based on evolution strategy
The publication concerns the reconstruction of the flaccid membrane surface shape based on information in an image obtained from a camera. The article includes results of the research, which aimed at optimizing the position of markers located on the surface of the flaccid membrane. The experiment used a membrane used in a model of an extracorporeal pneumatic heart assist pump. It was expected that the optimization of the position of the markers would increase the accuracy of modeling the shape of the membrane surface. The basis for modeling is the knowledge of the position of markers located in the R3 space. The coordinates of the markers were determined using a visual technique with the help of a camera. Coordinates determined in such a way were subjected to interpolation in three-dimensional space, and then were oversampled. The result is a grid representing the shape of the surface of the flaccid membrane. Evolutionary strategy was used to optimize the position of the markers. For this optimization, a unique design, selection method, a stopping condition method and an assessment function were proposed. The study was carried out for a convex membrane with a known mathematical description. Due to this, it was possible to determine the mapping error of the obtained membrane surface shape in relation to the shape of the reference surface (model), determined from a formula.
Model-based measurement of the stroke volume of a VAD in close-to-real conditions
The presented research concerns the determination of the pulse discharge volume of an extracorporeal pneumatic heart assist pump. The publication proposes a method for measuring the discharge volume based on the shape of the surface of the flaccid membrane, which is the pressing element of the pump. The membrane shape was obtained using image processing and analysis methods. The effectiveness of the proposed approach has been experimentally verified and confirmed by the authors. However, firm models of flaccid membranes were used in these studies. This work concerns the verification of the operation of the developed method of measuring the discharge volume in close-to-real conditions. For this purpose, an artificial heart chamber model was used along with a designed and produced measuring system. The article presents the laboratory station, the course of the experiment, obtained results and conclusions.
Analysis for the sensitivity optimization of integrated optical evanescent wave sensors with grating couplers
The structure composed of a single mode silica-titania slab waveguide on a BK7 glass substrates and a grating coupler embossed at the interface of slab waveguide to ambient is studied. Reported studies are focused on optimization of thickness of the slab waveguide, length of grating period and coupling angle, aiming at maximization of coupling angle homogeneous sensitivity, which is a product of effective index coupling angle sensitivity and slab waveguide homogeneous sensitivity. If effective index coupling angle sensitivity is varying with grating period then it has a local minimum. At this minimum coupling angle homogeneous sensitivity depends only on slab waveguide homogeneous sensitivity and a refractive index of medium where coupling angle is measured. Effective index coupling angle sensitivity is monotonous if is varying with waveguide film thickness. Monotonicity sign depends on grating period. Coupling angle homogeneous sensitivity considered a function of waveguide film thickness may have local maximum. However, depending on grating period, it can also be strictly increasing or decreasing function of waveguide film thickness, depending on a diffraction order, in which case it becomes very high. However in this case, coupling angle is quickly increasing and reaches π/2.
Influence of near UV irradiation on ZnO nanomaterials NO2 gas sensing properties
Marcin Procek, Agnieszka Stolarczyk
The paper presents gas sensors based on ZnO nanostructures, which were obtained from zinc acetate in a very simple and repeatable process. Obtained structures were characterised using Raman spectroscopy and scanning electron microscopy. The ZnO nanostructures were applied as receptor layers in chemoresistive gas sensors onto interdigital transducers, using drop-coating. Sensor responses to low concentrations (1 ppm) of NO2 in the air, at different operating temperatures (room temperature 23°C (R.T.), 100°C and 200°C) and under different lighting conditions (dark conditions and UV irradiation – LED λ = 390 nm) are compared and discussed. Obtained results show that proper combination of elevated temperature and illumination by UV can improve sensor properties and allow it to operate at a lower temperature.
Study of the impact of the object's location on the image on the results of distance measurement by the DFD technique
The aim of the paper is to determine the impact of the object’s location in relation to camera's optical axis on the distance measurement using the method belonging to the Depth From Defocus (DFD). The method has been developed to determining the shape of flaccid membrane used in Ventricular Assist Device (VAD). The tests were carried out in laboratory conditions. The research were carried out using a fixed miniature camera and a fixed focal length lens. The camera observed a marker with a diameter of 0.003 m, in various position relative to the optical axis perpendicular to the plane of the marker. The position of the marker was changed in three dimensions, with a 0.001 m step, in the range from 0 m to 0.010 m in directions according to X and Y. The Z direction was researched in the range from 0.100 m to 0.140 m with a step equal 0.001 m. The measurable effects of work are the recommendations regarding the correction of the distance measurement depending on the marker shift relative to the camera optical axis.
Copolymer grafted phthalocyanine-based fiber optic nitrogen dioxide gas sensing
In this paper, a simple combination of dip-coating fabrication techniques and cost-efficient copolymer grafted phthalocyanine material for the fabrication of fiber optic NO2 sensor was investigated. A fiber optic sensor was fabricated by organic thin films immobilized on the end-face of an optical fiber. Sensing nanostructure were formed on the end-face of an optical fiber by dip-coating method from liquid phase. Polymeric thin film work as sensitive elements and transducer to get optical response and feedback from environments, in which optical fibers are employed to work as signal carrier.
Structural and optical characterization of the high quality Be-doped InAs epitaxial layer grown on GaAs substrate
Jarosław Wróbel, Kacper Grodecki, Djalal Benyahia, et al.
The highly Be-doped InAs layer has been grown on semi-insulating GaAs (100) substrate by Molecular Beam Epitaxy. Very good quality of the layer has been attested by high resolution scanning electron microscope (HR-SEM), X-ray diffraction (XRD) and the Raman spectra. The parallel and perpendicular residual strain are determined to be – 1.17 × 10-3 , and 1.12 × 10-3 , respectively. Moreover, the absorbance (ABS) and photoluminescence (PL) spectra were collected in order to estimate the bandgap narrowing. The 10 meV bandgap shrinking for 1.7×1018 cm-3 acceptor concentration suggests necessity of reexamining the Jain et al model [Jain, S. C., et al. - JAP 68(7): 3747-3749] in the context of actual values of InAs valence-bands effective-masses.
InAsSb photoluminescence at low temperatures
K. Murawski, K. Grodecki, P. Martyniuk
In this work we present photoluminescence measurements of InAs 0.916Sb0.084 bulk material grown in MBE VIGO/MUT laboratory [1–2]. Photoluminescence spectra showed the occurrence of two peaks in temperature range 20K-40K, one of them comes from the band-to-band transition while the another is the result of exciton transition [3].
Theoretical investigation of properties of InAsSb mid-wave infrared detectors
In this work we present the theoretical investigation of the electrical and optical properties of high operating temperature (HOT) mid-wavelength infrared detectors (5 μm at 230 K) based on InAsSb/AlSb heterostructures [1]. In this work the performance comparison of barrier detectors with different doping concentration of n-type absorbing layer is presented. The barrier structure was simulated by commercially available software APSYS. We report on the dependence of the calculated current responsivity on the active layer thickness for a different doping concentration and doping concentration for optimal absorber thickness. Moreover, we show the influence of the bottom contact material on device’s performance.
Selected technological aspects of semiconductor samples preparation for Hall effect measurements
Kinga Gorczyca, Jacek Boguski, Jarosław Wróbel, et al.
The article presents comparison of two alternative method of Hall sample preparation–manual "square" shaped and the cloverleaf one made by full photolithography process. The influence of symmetry and contacts configuration on repeatability of 4-point resistance and Hall resistance versus magnetic field characteristics was a Hall sample quality criterion. The characterization was performed in ±15 T magnetic-field range at 80 K and 300 K, for undoped InAs epitaxial layer, deposited on the GaAs substrate using MBE. It was indicated that the sample made by photolithography had better usefulness for Hall characterization, showing broader magnetic field range by two orders of magnitude than the reference one.
Investigating the possibility of using a neural network to determine the stroke volume of a new pneumatic heart prosthesis model
The work concerns the study of the possibility of using an artificial neural network to determine the ejection volume of pulsatile models of heart assist pumps. The research used new pump designs, significantly different from those used in terms of dimensions and the material from which the flaccid membrane was made. The basis for determining the ejection volume are the special features of the membrane view, which is obtained from the vision sensor. The essence of the method operation depends on associating the membrane view with the corresponding reference volume value, which during the network learning process, is read from the burette with an accuracy of ±0.5 ml. The operation of the artificial neural network consists in the identification of artifacts on the examined views of the membranes and associating them with the ejection volume values. In the case where the membrane view cannot be univocally qualified to the training set, the network acts as an interpolator and predicts the stroke volume value. Verifying the ability to determine the stroke volume by the neural network was performed in close-to-real conditions. In addition to the test results, the article presents new pump designs, the laboratory station and the course of the experiment.
Luminescence spectroscopy diagnosis system for skin cancer research: k-Nearest Neighbour method classificator
P. Kałużyński, D. Kogut
A precision classification of neoplastic change plays very important role in cancer diagnosis. Because of constantly developing technology, the amount of information received is also increased. The ability to distinguish between tumor classes (in different kind of tissues) by using spectra data is an novel and promising approach to cancer classification. In this paper, we present a classification spectra data by k-Nearest Neighbor (kNN) method, which can and will be used for luminescence spectroscopy skin cancer diagnosis system.
System for visualization of hypodermic blood vessels
The paper presents the effects of the work aiming to build a device for spatial visualization of hypodermic blood vessels. The device was built using illuminators radiating polarized light of wavelength λ = 850 nm and two cameras in a stereoscopic set up equipped with polarizers and interference transmission filters, matched to illuminators. Images captured by cameras were analyzed by software that increases the contrast of blood vessels and extracts information about the distance from the hypodermic blood vessels to cameras. In this way the extracted course of blood vessels is recorded in the widely used in medicine DICOM format.
Long term stability study of InAsSb mid-wave infrared HOT detectors passivated through two step passivation technique
K. Michalczewski, F. Ivaldi, Ł. Kubiszyn, et al.
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.
Higher operating temperature photoresponse of MWIR T2SLs InAs/InAsSb photodetector
Krystian Michalczewski, Tsung-Tin Tsai, Piotr Martyniuk, et al.
We investigate the photoresponse of mid-wavelength infrared radiation (MWIR) type-II superlattices (T2SLs) InAs/InAsSb high operating temperature (HOT) photoconductor grown on GaAs substrate. The device consists of a 200 periods of active layer grown on GaSb buffer layer. The photoresistor reached a 50% cut-off wavelength of 5 μm and 6 μm at 200 K and 300 K respectively. The time constant of 30 ns is observed at 200 K under 0.5 V bias. This is the first observation of the photoresponse in MWIR T2SLs InAs/InAsSb photocondotocr above 200 K.
The method of determining the characteristic features of graphene oxides by atomic force microscopy
In this paper, we present the results of the measurements obtained using atomic force microscopy (AFM). The subject of research were the reduced graphene oxides which were obtained by oxidation (in first step) of the graphites and thermally reduction (in the second step). The three types of graphites (flake, scale and synthetic) and three different method of oxidation were used in the measurements. The special attention was paid to the height and horizontal sizes of the obtained material. The results was analysed and relevant conclusions were drawn from them.