Abstract:Typically, infrared detectors require cryogenic cooling to limit dark current which is directly dependent on Auger generation-recombination mechanism and highly influential in HgCdTe-narrow band gap material. The Auger suppressed architectures have an advantage over conventional detectors allowing operation at elevated temperatures >200 K. Architecture with combination of exclusion and extraction heterojunctions has been proposed to lower Auger contribution. The paper presents a new long-wave (≈ 10 μm) infrared HgCdTe architecture with graded gap/doping interfaces and extra barrier located in exclusion heterojunction to suppress dark current for high operating temperature conditions. Proper barrier implementation reduces dark current by more than 20 A/cm2 for room temperature operation.

Abstract:GaSb polycrystalline thin films were prepared on ITO substrate with the method of PVD. By controlling substrate temperatures and thicknesses of GaSb films, surface roughness, grain size, electrical and optical properties were investigated. The preferred orientation of GaSb thin films grown on ITO substrate had changed from GaSb (111) to GaSb (220) under specific growth conditions which had never occurred on glass substrates. GaSb thin films with (220) preferred orientation had higher hall mobility because of less grain boundaries and less defects. The thin films after optimization possess, the absorption coefficients over 104 cm-1, which is desirable in the application of TPV thin film cells.

Abstract:The effect of copper phthalocyanine (CuPc) buffer layer on open circuit voltage in indium tin oxide/zinc phthalocyanine (ZnPc)/C60/CuPc/Al devices is investigated. A dependence of the open circuit voltage on the thickness of CuPc layer is observed. We analyze the current-voltage curves under illumination based on semiconductor device theory. A high ideality factor is found as the reason for the high open circuit voltage. We propose that both ZnPc/C60 junction and CuPc/Al contact contribute the high ideality factor. Our result shows that the open circuit voltage may be improved by introducing an extra rectifying buffer/cathode junction.

Abstract:The fixed pattern noise of uncooled infrared focal plane arrays has the similar characteristics with the stripe noise. By researching the moment matching and temporal high-pass filter, a novel multiscale temporal moment matching nonuniformity correction algorithm was proposed. In the proposed algorithm, global motion was first identified by the Gaussian pyramid of the adjacent uncorrected images. Then the temporal moment matching was performed in all levels of Gaussian pyramids and Laplacian pyramids. The experimental results with the real infrared video sequences have shown that the proposed algorithm can significantly increase the convergence speed and reduce the ghosting artifacts.

Abstract:A highly-tunable wide-angle metamaterial absorber with perfect absorption and polarization-insensitivity was introduced and investigated. Simulative results show the maximum absorption reaches up to 99.9% at 5.8 μm and the absorber can be tuned arbitrarily in the range of 3.4 μm to 8.6 μm with the absorption remaining above 95% by changing its geometric parameters. The absorber remains absorptivity of over 95% with incident angles below 80° under transverse magnetic(TM) polarization and that of over 92% below 60° under transverse electric(TE) polarization. Furthermore, the absorber is polarization insensitive with polarization angle varying from 0° to 90°.

Abstract:Target spectral signature is modeled firstly based on the thermal radiation theory and a multispectral background suppression approach is given. An experimentally justified assumption is made that the probability density functions (PDFs) of the feature vector can be modeled as Gaussian random process, and then a new unifying radiation intensity and radiation spectral signature (URIS) detector is developed. Finally, performance analyses based on a set of multispectral imagery and receiver operating characteristic (ROC) curves are presented. According to the experimental results, the URIS method can successfully detect dim point target in rather low signal-to-noise condition.

Abstract:This paper proposed a method, namely resistively loaded lines (RLL), to compensate the effects of the DC bias lines after investigating its effects on several types of antennas for terahertz photomixers. The RLL is formed by placing lumped resistances periodically on the DC bias line in order to cease the leakage current virtually, which cause a significant amount of distortion on the antenna performance. The simulation results of the dipole, folded dipole, log-periodic, and spiral antennas show that RLL almost removes the effects of the bias lines and improves the antenna radiation resistance and radiation pattern notably compared with that of the commonly used bias line types, such as coplanar stripline and photonic bandgap type bias lines.

Abstract:1.25-GHz high speed short-wavelength infrared single-photon detector (SPD) based on InGaAs/InP avalanche photodiode (APD) 1.25-GHz sine wave gating and Bessel LC low-pass filters (LPFs) was described. The avalanche signal amplitude distributions of the SPD at different reverse DC biases are studied experimentally by adjusting the discrimination level of the comparator circuit. As the discrimination level is raised, both detection efficiency and dark count rate reduce exponentially, while the after-pulse probability firstly rises to a peak value and then reduces. It indicates that the discrimination level should be as low as possible to obtain better SPD performance.

Abstract:Au-doped Hg1-xCdx Te epitaxial layers were grown by vapor phase epitaxial method. The electrical properties of Hg1-xCdxTe epitaxial layers were investigated by Hall measurement. Profile of Au in Hg1-xCdx Te epitaxial layers was revealed by Secondary ion mass spectroscopy (SIMS) method. Hall coefficient and Hall mobility of three abnormal P type samples were discussed. Moreover, variable-magnetic-field Hall measurement was performed on Hg1-xCdx Te with antitype epitaxial layer. Mobility spectrum analysis was employed to verify surface electrons, bulk electrons and bulk holes mixed conduction in Hg1-xCdx Te epitaxial layers.

Abstract:The far-infrared reflectance spectra and the infrared detection characteristics of the new infrared material of InN0.01Sb0.99 thin films were reported. Far-infrared reflectance spectra, blackbody photoresponses and photocurrent spectra of the lattice mismatched InN0.01Sb0.99 film on GaAs substrate have been measured. A prototype wide-band infrared detector whose response peak at 4.4 μm and cut-off wavelength at 5.7 μm with the FWHM of 3.5 μm has been obtained. By investigating the annealing effects on the device performance, it is found that the crystal quality and the response capability are improved and the Moss-Burstein effect is reduced after annealing.

Abstract:The optical properties of Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 single crystal near morphotropic phase boundary were investigated by temperature dependent transmittance and reflectance spectra. The temperature dependent absorption edges show blueshifts below 300 K while they show redshifts above 300 K. At 303 K, optical band gap Eg is 3.25 eV, critical point energies Ea and Eb are 3.93 and 4.65 eV, respectively. With increasing temperature, Eg, Ea and Eb decrease and they are 3.05, 3.57, 4.56 eV at 453 K, respectively. Three critical point energies Eg,Ea and Eb are corresponding to O 2p to Ti d, and Pb 6p, respectively. Such narrowing trends with increasing temperature can be explained by thermal expansion of the lattice and electron-phonon interaction. Based on Tauc-Lorentz dispersion models, the dielectric functions from 3.1 to 6.5 eV have been extracted from303 to 453 K. It was found that the refractive index n increases with increasing temperature.

Abstract:La doped BiGaO3 (LxBGO) films were fabricated by the Sol-Gel method on the Pt/Ti/SiO2/Si substrates. X-ray diffraction analysis shows that the films are polycrystalline with an orthorhombic structure. The atomic force microscopy images of the LxBGO films suggest that the surface morphology is smooth. The optical properties of the samples were investigated by the spectroscopic ellipsometry in detail. The dielectric functions were extracted and in good agreement with the Adachi dispersion function. More one step, the optical band gap tends to increase with increasing La composition, which is consistent with the results of theoretical prediction. These results are helpful for the fabrication of Bi-based opto-electrical devices such as ultraviolet detectors.

Abstract:Synthetic aperture radar (SAR) is a microwave remote sensing radar with capability of all-day and all-weather imaging. Millimeter-wave SAR has become important for development of SAR with the advantage of small volume, light weight, and high resolution. The basic principle for high resolution imaging of millimeter-wave SAR is analyzed, and the advantage of millimeter-wave SAR is present. The state-of-art in the development of millimeter-wave SAR technologies and systems are illustrated with some typical millimeter-wave SAR systems. The application prospects, some issues, and future development trend of millimeter-wave SAR are also discussed.

Abstract:Firstly, the basic principles infrared radiation characteristic measure was presented. Due to the diffraction effect of the optical system, point target’s image is a dispersed spot. Point target radiation characteristic measurement accuracy is generally very low. View of this situation, one point target radiation characteristic measurement optimization algorithm based on radiation energy conservation was proposed, Specific principles and implementation process was given. Finally, point target radiation characteristic measurement experiment was done, and the results were analyzed. The results show that the point target radiation measurement optimization algorithm’s accuracy is better than 10%, indicating that the point target radiation characteristic measurement optimization algorithm has large application prospects in practice.

Abstract:Based on the total differential and statistical theory, the analytical expressions of the synthesis horizontal wind speed and direction error are derived. Using Cramer-Rao lower bound instead of Frehlich’s empirical formula, the random wind errors are evaluated, and then a universal horizontal wind speed and direction error calculation modeling is established. Based on the design framework proposed by NASA / NOAA, a combination of simulation parameters is selected for the feasibility analysis of the error modeling. The Changing relation of the total radial random error and the detect range and the horizontal wind range is drawn. Meanwhile, in order to calculate the sampling error, a combination of vertical resolutions and orientation angles is chosen for comparative analysis. The results show that by using this mode the synthesis horizontal wind speed and direction errors are in the range of 0.8 ~ 3.2m / s and 2.38 ° ~ 3.49 °respectively, basically in line with relevant requirement indicators.

Abstract:In this perspective, we reviewed the fabrication technologies of various silicon micro-nano structures and their applications in novel type of solar cells. The recent progress in the application of silicon micro-nano structures in traditional p-n junction solar cells, radial p-n junction solar cells and hetero-junction solar cells are discussed respectively. We then shown the recent efforts to improve the energy conversion efficiency of the solar cells with silicon micro-nano structures, including enhanced absorption of incident light, as well as surface modification and surface passivation of silicon micro-nano structures. Finally, brief overview and outlook are provided on the development of flexible silicon solar cells.

Abstract:Monocrystalline silicon and single junction GaAs/Ge solar cells irradiated by 16 ns pulse-duration with the laser at 1064 nm wavelength for different fluences (energy densities) were studied. It was found that solar cell is easily damaged when laser spot was focused on the metal gridlines, meanwhile, monocrystalline silicon solar cell was almost undamaged when laser spot was focused on the surface, GaAs/Ge solar cells’ performance didn’t decrease greatly. Theoretically, the damage of nanosecond pulse mainly commons heat and dynamics effects. The high temperature melts and gasifies materials and the dynamical effect is along the laser’s transmitting direction vertical to the surface of materials. Investigation also indicates that monocrystalline Si cells and the thick germanium base intrinsically absorb 1064 nm strongly, while the GaAs/Ge is transparent to 1064 nm, The melting point of germanium material is lower than that of silicon, so its damage threshold is lower. These experimental conclusions were proved and verified by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS).

Abstract:Because that there are obvious differences of radiometric and geometric in SAR and optical image registration, this article presents a method based on cascade transform (CT) to register SAR and optical images. To remove radiation differences, gray transformation was used to extract stable structure information for the SAR and optical images. Then, Weighted-Logarithmic-Polar transformation is proposed to obtain scale and rotation parameters between the images, solving the global geometric differences. Finally, local geometric transform is conducted to get accurate matches and the image was registered by TPS model. The registration experiments show that the proposed method is able to extract stable structures and robust to the differences of radiometric and geometric. The precision of the registration method is high.

Abstract:A radial extended interaction oscillator has been presented in this paper. This new structure has characteristics such as compact structure, good heat dissipation and high output power. The characteristics trends of 4-cavities radial EIO has been determined through the analysis of a single coaxial resonator gap. And the operating frequency and voltage is more accurately tested by simulation of electromagnetic simulation software and small signal theory analysis. Since the electron emission surface of the electron gun of radial EIO is much larger than that of conventional EIO, so in the case of small current density, a large current can be obtained. When the voltage is 5kV and the current is 8.48A, the PIC simulation shows that the radial EIO could generate 2.6 kW in 30.011 GHz.

Abstract:This paper proposed a new pixel decomposition model of Temperature Unmixing with Spectral (TUS). Landsat TM data acquired in Beijing were used for the study. Firstly, land surface fraction was obtained based on the Linear Spectral Mixing Model.Secondly and LST of typical endmember was selected through Temperature Vegetation Index. Finally, pixel decomposition of LST can be achieved integrated emissivity with different surface components. Our results indicated that TUS can effectively improve the spatial resolution of land surface temperature, reflecting the spatial differences of surface components, with MAE and RMSE 1.25K and 2.27K respectively. Therefore we conclude that TUS model is applicable for decomposition of LST images for high spatial resolution in the complex surface coverage area.

Abstract:In this paper, the Doppler radar tomography is investigated and the theoretical spatial resolution is analyzed. Then the algorithm of the Doppler radar tomography based on convolution back-projection method was proposed. Finally, some measurement results of imaging using 662 GHz single-tone signals were presented.