Abstract:Cu2ZnSnS4 (CZTS) films with a smooth and compact morphology were obtained via a sol-gel process. Raman spectra and X-ray diffraction (XRD) results indicate that all the films have the kesterite structure. Energy dispersive X-ray spectroscopy (EDS) suggests that all of CZTS films are of S-deficient, Cu-poor and Zn-rich states. The thickness of all the films is around 0.7μm measured by a field emission scanning electron microscope (FE-SEM). Transmission spectra reveal that the optical band gap (Eg) of samples reduces from 2.13 to 1.52eV as post-annealing temperature goes up.

Abstract:A novel type resonant infrared (IR) detector based on microbridge resonators electrothermally excited and piezoresistively detected using polysilicon resistors of negative temperature coefficient of resistance (TCR) was presented. The temperature rise of microbridges due to absorbed infrared radiation reduces the resistance of the excitation resistors and Wheatstone bridges. As a result, both the static component of the exciting power and the Joule heat of Wheatstone bridges accordingly increase with reducing the resistance. It is equivalent to increasing infrared radiation power. From preliminary experimental results, the feasibility of sensing infrared radiation is demonstrated.

Abstract:A two-dimensional direction finding ambiguity resolution algorithm about millimeter wave interferometer is proposed in the paper. By means of implementing one or more times virtual transformation operation on measured phase differences between the original circular array elements and the reference array element, the unambiguous phase differences between the virtual array element and reference array element are achieved. The unambiguous phase differences are used to give rough but unambiguous estimation of direction of arrival (DOA), which are used as coarse references to disambiguate the cyclic phase ambiguities in phase differences between the original array element and the reference array element. The high-precision estimations of DOA are acquired. Simulation examples have verified that the algorithm can obtain the two-dimensional direction finding results with high accuracy in the millimeter wave frequency range.

Abstract:Traditional methods for boundary regularization mainly take airborne laser scanning (ALS) data as input and process the point clouds of building roofs with simple planar shapes, while terrestrial laser scanning (TLS) could acquire more complete and denser point clouds of building facades with more complex shapes. In this paper a new boundary regularization approach based on TLS data is proposed. It can deal with several types of point clouds for buildings facades, including walls, doors and windows. Firstly, raw point clouds are segmented into planar facades by using an efficient RANSAC algorithm. Secondly, the boundary points are extracted by using a 2D α-shapes algorithm. Based on the boundary points, a fitting regular polygon is generated by using the boundary regularization approach proposed in the paper. The experimental results show that the proposed approach is self-adaptive to point clouds with different density. Meanwhile, it is demonstrated that the approach is effective and efficient, and could provide reliable and satisfactory regularization results.

Abstract:The optical transmission characteristic of colloidal photonic crystals with core @shell structure has been calculated via the finite-difference time-domain (FDTD) method. The core @shell structure has been designed using the low-dielectric Fe3O4 core and high-dielectric TiO2 shell. The results show that the behaviors of stop band can be adjusted by the effective permittivity and core @shell size ratio of materials. With the increase of permittivity, the stop bands show redshift and bandwidth increase. When the overall size of core @shell is constant, the stop bands show blueshift with the increasing core diameter, and the maximum bandwidth (Δλ/λ) reaches 33.4% when the diameter ratio between core @shell and core is 150nm: 130nm. When the core size is constant, the stop bands show redshift with the increase of the overall size of the core @shell structure. The minimum thickness of TiO2 shell that can make the stop bands appear is 3nm in the Fe3O4@TiO2 core @shell structure.

Abstract:A new scheme of wavelength switching in multiuser near-infrared quantum cryptography networks has been proposed. Solution is provided for information exchange in quantum network, the unchanged polarization in the course of switching is also analyzed. In addition, the relation between conversion efficiency and pump power is simulated. The results show that this scheme is feasible and effective.

Abstract:Spinel oxide Mn-Co-Ni-O (MCNO) thin films were prepared by using a chemical solution deposition method (CSD). The electrical property and device performance based on MCNO thin films were investigated, including the responsivity (RV), noise spectra and the detectivity (D*). MCNO thin film with a thickness of 8μm was prepared and their sheet resistance versus temperature curves are measured. The optical immersed MCNO infrared detector based on Germanium lens was fabricated, and it possesses the advantages of relatively small time constant (～18ms), high responsivity (～4.4×103V/W) and high detectivity (～5×108cm·Hz0.5/W).

Abstract:The transient photovoltaic responses in InAs/GaSb type-Ⅱ superlattice infrared photodetectors under picosecond pulsed laser illumination are reported. By analyzing the dynamic processes in the transient response curves of the p-b-i-n structured type-Ⅱ superlattice detectors, the apparent carrier lifetime can be obtained. A series of single element devices with different mesa areas have been investigated. The minority carrier lifetime trends to increase as the mesa area increases, implying a reduced surface recombination resulted from the un-passivated side-walls of the mesa. The investigated minority carriers are attributed to holes, with the apparent lifetime in the range 2-12ns.

Abstract:A two-dimension numerical analysis for the electrical characteristics of Si/strained Si1-xGex/Si hetero-junction-on-insulator p-MOSFET has been complished. The characteristics of the threshold voltage, transfer and output were studied. The results indicate that the value of the threshold voltage has a positive offset and the transfer characteristics are improved with increase of Ge content. The growth rate of the drain-source current becomes lower with the increase of Ge content under a fixed bias voltage on the device, compained by obvious kink in the output characteristics.

Abstract:A new preprocessing method used for target detection in hyperspectral imagery was proposed. This preprocessing method can increase target spectra accuracy, so the performance of the target detection methods can be improved. By using the target spectra gotten from the laboratory and field as references, the proposed method extracts independent components, which are the closest to the references, from the hyperspectral imagery by means of independent component analysis with references (ICA-R). Then, these independent components are used as target spectra in the following supervised target detection methods. Experimental results on both simulated and real hyperspectral data demonstrate that the proposed method can get more accurate target spectra, which obtains much better performance of target detection.

Abstract:A model of the metal-grating periodic slow-wave structure (SWS) with dielectric loaded in the grooves was built and the expressions of the dispersion equation and coupling impedance were developed by using the Borgnis function and the field-matching method. Under the assumption of the dilute electron beam, the gain was obtained. Through numerical calculations, the influences on the high-frequency characteristics of some parameters are given. Moreover, the different characteristics of the two ways of the dielectric being loaded have been analyzed.

Abstract:According to the level of domestic processing technology at present, the circuit structure of anti-parallel diodes with self-bias was proposed. With this structure, not only the difficult problem of processing bias circuit can be solved, but also the odd-order frequency multiplication can be realized efficiently. At the meantime, co-simulation approach was used to simulate the electrical characteristic of the tripler by software HFSS and ADS, including the impact of the parastics. After designing, both the machining and electrical installation are accomplished. The highest measured output power is 3.1mW at 221GHz and the output power is more than 2mW at frequencies of the range 219～227GHz. These results can provide important reference for future design of high efficiency submillimeter frequency multiplier.

Abstract:The evolutional waveforms and spectrograms of sech, gaussian pulse (m=1) and supergaussian pulse (m=5) generated in normal dispersion region of high nonlinear fiber were numerically studied. The results indicate that the tail at both front and back edge of the pulse not only affects spectrum broadening, but also the flatness of supercontinuum. The chirp of pump pulse has little impacts on the generated supercontinuum. The pulse with high power, steep edge and small tail is preferable to generate wideband and flat supercontinuum.

Abstract:Based on five filed cruises in 2011 from Taihu Lake, the effect of particulate organic carbon (POC) assembles on remote sensing reflectance of water was performed to develop a new POC estimation algorithm for eutrophic inland waters. The optical model was used with monthly MERIS data to assess the temporal and spatial variability of surface POC reservoirs in Taihu Lake. The results demonstrated that the particulate organisms highly controlled the remote sensing reflectance of water in the range of 560～709 nm in this lake. The approaches from ocean color did not provide good estimates of POC concentrations in Taihu Lake, a more optically complex water dominated by inorganic detritus. By investigating the optical properties of the eutrophic water, we found that POC was distinctly correlated to the remote sensing reflectance ratio (Rrs(620)/Rrs(709)) with high R2=0.75 and low RMSE=33.27%, the correlation of which provided a good estimate of POC concentrations in Taihu Lake.

Abstract:The net radiation, ground heat flux, sensible heat flux and latent heat flux over the Northern Tibetan Plateau at different times of the day were estimated by using land surface observation, the surface energy balance system algorithm, and FY-2E geostationary meteorological satellite visible infrared and FY-3B polar-orbiting satellite microwave remote data. The results from the model agree well with the ground observations from Naqu Alpine Climate Stations with 28.22W·m-2 RMSE in hourly scale. The condition expectation of surface energy components during the summer time of the Northern Tibet were analyzed, and different surface temperature corresponds to the effective energy distribution were also discussed. The results shows regional ET was ranged between 2.0～ 4.0mm over the Northern Tibetan Plateau.

Abstract:A high speed 1053nm superluminescent diode (SLD) with ridge-waveguide structure has been fabricated. By optimizing of the growth parameters such as temperature, growth rate, epitaxial materials with excellent crystal quality were attained. The photoelectric characteristics of the SLD depended on temperature and driver current were analyzed. The coefficient of the wavelength shift with temperature was 0.35nm/℃.The wavelength of the SLD shift with driver current insensitive to the temperature. A -3dB cutoff frequency of 1.7GHz was obtained at a DC bias current of 100mA and 25℃,corresponding to 2.5mW output power from single mode fiber (SMF) with spectral modulation of less than 0.15dB and spectral width of 24nm.

Abstract:An integrated miniaturized portable entanglement source with high-brightness and high-stability has been designed using quasi-phase matching and Sagnac loop structure. Based on parametric down conversion process of PPKTP crystal, the entanglement source has the brightness of 13.8Mcps, the polarization contrast better than 98%, the tangle of 0.9357, and the jitter of counts rate caused by temperature variation and mechanical vibration less than 5%. The system has been successfully and effectively applied to the field test of 100km quantum entanglement distribution and lower-limit measurement of association speed under continuous running, which provides a good trial basis for further realizing the spatial entanglement source load.

Abstract:RF structure of W-band sheet beam EIK has been designed in this paper. The interaction system consists of two five-gap cavities, one is used for input cavity, the other is output cavity. The whole beam wave interaction system has been calculated and simulated by two kinds of 3D-PIC software, and the results agree well. Beam voltage of the SBEIK is 75kV, and beam current is 4A. The gain of whole tube is higher than 24dB, which is only consisted of two resonant cavities. If there are more cavities, the tube will get higher gain. This is a big progress and is very useful for the design of multi -cavities SBEIK.

Abstract:A novel mixed noise estimation method based on the spectral and spatial information of hyperspectral images was reported. Firstly, homogeneous image blocks were automatically detected using data masking. Then signal value and noise value of each pixel in homogeneous blocks were split with a multiple liner regression model. Meanwhile, rough approximations of SD and SI noise were obtained. Finally, likelihood function was built based on the mixed noise model, where parameters of the noise model were calculated by maximum-likelihood estimation approach. The proposed method is demonstrated to be accurate and robust by experiments with both synthetic images and real hyperspectral images.

Abstract:Based on Gaussian decomposition of the geoscience laser altimeter system(GLAS) waveform, accurate waveform characteristics were extracted, and then laser penetrate index (LPI) was computed for each GLAS waveform. The new method of leaf area index (LAI) estimation using LPI derived from GLAS data was proposed. Forest LAI estimation model based on GLAS data was established(R2=0.84, RMSE=0.64)and the models reliability was assessed using the Leave-One-Out Cross-Validation (LOOCV) method. The result indicates that the regression model is not overfitting the data and has a good generalization capability. Finally, regional scale forest LAI was estimated using combined GLAS and TM optical remotely sensed image by artificial neural network. And then, the accuracy of the predicted LAIs based on neural network was validated using the other 25 field-measured LAIs. The results show that forest LAI estimation are very close to the field-measured LAIs with a high accuracy (R2=0.76, RMSE=0.69). Therefore, the estimated LAIs provide accurate input parameters to the study on ecological environment. The study provides new methods and ideas to estimate LAI with large regional scale using GLAS waveform data.

Abstract:Adjacency effect of the optical remote sensing could be regarded as the convolution of the atmospheric point spread function(PSF) and the surface-leaving radiance. By simulating the atmospheric PSF with backward Monte Carlo method and calculating the surface-leaving radiance with MODTRAN model, the at-sensor radiance was obtained. The adjacency effects for different target and background under different propagation conditions were simulated and analyzed. The results show that target and background reflectivity affect adjacency effect significantly and the percentage of the radiance caused by the adjacency effect in the total radiance increases with the increase of the background reflectivity. Adjacency effect for dark target under bright background is more obvious than that for bright target under dark background. Given imaging height and area, the higher the imaging space resolution, the stronger the adjacency effect is. Effect of the surface meteorological range on adjacency effect is of high importance. The larger the surface meteorological range, the bigger the sun zenith angle, the weaker the adjacency effect is. These results could provide the basis for modeling the optical remote sensing imaging system with high precision and exploring the correction algorithm of the adjacency effect.