Abstract:To study the guardring suppression effect on the extension of the photosensitive area in planartype front illuminated InP/InGaAs heterostructure detector，the InGaAs photo detectors with different distances between guardring and PN junction were designed and fabricated. The actual distance between guardring and PN junction of the detector was calculated based on the atomic force microscopy (AFM) and scanning capacitance microscopy (SCM) measurements. The characteristics of the photo response of the detectors with guardring were carried out with laser beam induced current (LBIC) method. It was indicated that LBIC signal of the photo detector without guardring fit well with the exponential decay function, while that of detector with guardring followed the Gaussian distribution. The extension value of the photosensitive area decreased linearly as the distance between the guardring and PN junction decreased. It was concluded that the appropriate gap between the guardring and PN junction should be in the range of 7 to 12 μm.

Abstract:Poly (vinylidene fluoridetrifluoroethylene) (P(VDFTrFE)) thin films were deposited on polyimide substrate using horizontal LangmuirBlodgett(LB) technology. Xray diffractions indicate that the films have good crystallinity with (110) preferential orientation for films with different thickness. The optical dispersion of the films were measured by variableangle spectroscopic ellipsometry. The data Ψ and Δ at multiple incident angels (θ=75° and 85°) were fitted using the Cauchy model. The refractive index, extinction coefficient，absorption coefficient and thickness of each film were obtained. The ferroelectric of the films were studied. The remnant polarization is up to 6.3μC/cm2. The coercive field is 100MV/cm. The dielectric measurement for the film shows two distinctive phase transitions, ferroelectricparaelectric phase transition and β relaxation.

Abstract:An airborne inspection technique of natural gas transport pipeline based on the near infrared wavelength modulation spectroscopy is proposed. The physical principle of this technique was interpreted. The applicability of this technique to the helicopter station was discussed. The field experiments were carried out on a homemade system to validate the engineering feasibility of the technique.

Abstract:The results of 128×128 SW/MW twocolor HgCdTe infrared focal plane arrays (IRFPAs) were presented. By B+implantation, mesaisolation etching, sidewall passivation, sidewall metallization and flipchip hybridization with readout integrated circuit (ROIC),128×128 SW/MW twocolor HgCdTe IRFPAs detector was fabricated from a fourlayer ppPN heterojunction of Hg1-xCdxTe film grown by molecular beam epitaxy and insitu doping techniques. The micromesa fillfactor of (50×50)μm2 twocolor detector arrays was doubled by optimizing the wetchemical etching process. The staring SW/MW twocolor HgCdTe IRFPAs detector performed high uniformity and normal photoelectric properties. At liquid nitrogen temperature, the cutoff wavelengths of the twocolor IRFPAs were 2.7μm and 4.9μm, respectively, and the peak detectivities (D*λp) were 1.42×1011cmHz1/2/W and 2.15×1011cmHz1/2/W respectively. 

Abstract:Based on primary parameter analysis of the thermal infrared hyperspectral imaging system, several methods were proposed to overcome the difficulties in detecting objects with low signal energy, serious thermal infrared background radiation and other problems. A pushbrooming infrared hyperspectral imaging system was developed, which can suppress the high background radiation effectively, and the groundbased imaging experiment was realized. Based on the low background experimental results, the relationship of the system performance with different factors was analyzed, and feasibility to optimize the system performance was comfirmed.

Abstract:Thinfilms of lead tellurium selenide were evaporated on silicon substrates from a resource of PbTe0.92Se0.08 bulk crystal grown by Bridgman method. Xray diffraction (XRD), scanning electron microscope (SEM), and energydispersive analysis by Xray (EDAX) were used to characterize the structural and surface morphological properties, as well as chemical compositions of the thinfilms. The results indicate that thinfilms of lead tellurium selenide have a polycrystalline structure and a preferred orientation during the deposition. It was also revealed that the grains appear as rectangles. By comparison of the optical properties of the thinfilms deposited at different substratetemperatures, it was found that substrate temperature has an important effect on the infrared optical properties of thinfilms. The refractive index of the lead tellurium selenide thinfilms lies between 5.2 and 5.8, and the extinction coefficient is lower than 0.1. When the wavelength is greater than 6μm, the extinction coefficient of the thinfilms is as less as 10-3. It can be inferred that lead tellurium selenide is a potential material to be used in the infrared coatings.

Abstract:Based on chemical solutionprocess method, red, green, and blueluminescent CdSe/ZnS semiconductor core/shell quantum dots were successfully prepared by utilizing ethylxanthates as precursors of shell layers. Greenluminescent (542nm) and blueluminescent (483nm) core/shell quantum dots were synthesized by capping the CdSe core quantum dots with ZnS shell layers from zinc ethylxanthate precursors and manipulating reaction temperature with the presence of oxygen. The red color (612nm) CdSe/CdS/ZnS core/multishelled quantum dots were prepared by capping of CdS and ZnS shell layers from cadmium ethylxanthate and zinc ethylxanthate precursors. Results from UVvis absorption spectra, photoluminescence spectra and transmission electron microscopy (TEM) indicated that the emission redshifted if the ZnS capping of CdSe dots is processed at a lower temperature (about 230 ℃ ), while blueshifted at a higher temperature (about 260 ℃ ). Trichromatic white light was obtained via mixing of red, green, and blueluminescent quantum dots.

Abstract:Based on viscoplastic Anand model, von Mises stress distribution of the infrared focal plane array detector is analyzed by finite element method. Simulation results show that as the diameters of the indium bump decreases from 36μm to 18μm in step of 2μm, the maximum stress existing in InSb chip reduces at first, then increases linearly with indium bump diameters. Yet the stress distribution in the indium bump is almost unchangeable and its maximum value keeps at 15.7MPa. Furthermore the maximum stress in SiCMOS readout integrated circuit is smaller than that of InSb chip, and its changing tendency chart is almost the same as that of InSb chip. When the diameter of the indium bump is set to 30μm, the maximum stresses existing in both InSb chip and Si CMOS readout integrated circuit reach the minimal value 260MPa and 140MPa, respectively. Simulations also show that the stress distribution at the contact areas is uniform and concentrated, the stress value in the whole infrared focal plane array detector is smallest, and its distribution is promising.

Abstract:The dependency of the characteristics of 980nm high power verticalcavity surfaceemitting Lasers (VCSELs) on the distributed Bragg reflector (DBR) reflectivity was analyzed theoretically. The output characteristics of the VCSELs with different active region diameters were calculated. The output characteristics at different DBR reflectivities were analyzed. It is found that the variation of DBR reflectivity exerts different influences on the VCSELs with different diameters of active region. The test experiment was carried out in order to validate the theoretical analysis. The experimental results show that the output powers of VCSELs with 500μmdiameter active region under the injected current of 6A are 2.01W and 2.09W when the NDBR reflectivities are 99.7% and 99.2%, respectively. However， the output powers of VCSELs with 200μmdiameter active region under the injected current of 3A are 0.64W and 1.12W when the NDBR reflectivities are 99.7% and 99.2%, respectively. It was concluded that the theoretical results are validated by the experiment effectively.

Abstract:The eight neighborhood algorithm (ENA) was developed for estimating the variance of suspended sediment concentration (SSC) distribution in a pixel based on the current knowledge about the SSC retrieval models' scaling effect. Taking advantage of the results of ENA, further study developed the scaling correcting methods for linear quantitative models, exponential quantitative models and logarithmic quantitative models. Applied these methods to the results of the Landsat/TM imagery and the field spectral experiments in Tai Lake, it was found that the scale effect errors are strongly correlated with the SSC predicting models. The scale effect could result in 16% relative errors for reflectance measurement in complicated Case Ⅱ water bodies such as Tai Lake. 

Abstract:Pumping a 30cm length of photonic crystal fiber with a femtosecond Tisapphire laser, the supercontinuum spectrum scource of light in the near infrared region were generated. The wavelength ranges from 465nm to 2500nm, covering a wide band over 2000nm.The mechanism of the supercontinuum origination was studied.

Abstract:To improve the detection range of pyroelectric infrared sensor on the target (the pedestrian) , the passive infrared sensor detection system and IR signal were studied. The pyroelectric infrared sensor signal is affected by the perception parts on the target (pedestrians), temperature difference between the environment and objectives, lens size and sections related to the number. A detection system for testing infrared sensors distance were designed. Experiments showed that after taking into account several factors which affect the detection range, the detecting distance was improved from 10 meters to 40 meters while keeping the signal level of infrared detection unchanged. Test methods and results offer some guidance and reference for other similar detection systems. 

Abstract:Metallic wire gratings in terahertz frequency were designed and fabricated by femtosecond micromaching and sputtering technique. The polarized transmission spectra of the gratings were characterized by terahertz (THz) time domain spectroscopy. The theoretical simulations based on FDTD method show a good agreement with experimental results. The physical origin of impacting transmittance in S and P polarization was analyzed. The results obtained from this work provide a useful referrence for the production of THz polarization devices.

Abstract:Vanadium oxide thin films were deposited by dual ion beam sputtering, and then annealled with different procedures of temperature elevating. Optical transmission properties were measured at different temperature by use of Fourier transform infrared spectrum, from which the relationship of transmission and temperature at a fixed wavelength of 5μm was obtained. The results show that the vanadium oxide thin film annealed with rapid elevating temperature has smaller and uniform crystal size, while the film annealed with normal elevating temperature has larger and wider distributed crystal size. All the films after annealing have abrupt change over 60% in transmission in infrared band. The phase transition temperature of vanadium oxide thin film after rapid elevating temperature annealing is 63.74℃, which is higher than that of vanadium oxide thin film after normal elevating temperature annealing, 60.31℃. The temperature range of phase transition of the former is also broader.

Abstract:Because of the nonuniformity and instability of atmosphere, it is very difficult to obtain realtimely and precisely a band of infrared atmospheric extinction coefficient with MODTRAN atmospheric transmission software and any other traditional methods. The nonlinear function relationship between the input and output of neural network can be obtained via the relation among the atmospheric optical properties at different wavelengths in the nearinfrared band by generalized regression neural network. Then the atmospheric optical properties at other wavelengths can be further derived through realtime inversion of the data at certain wavelength measured by laser radar. The method was proved to be effective in obtainning realtimely the nearinfrared atmospheric optical properties of a band in actual combat conditions.

Abstract:Midcourse ballistic target, releasing warhead and large numbers of decoys and forming dense cluster, presents a new challenge for target tracking with spacebased infrared focal plane array ( IRFPA ). The numbers of the identified target vary because of the finite resolution of IRFPA. The target trajectory on IRFPA shows strong nonlinear characteristic. To cope with these problems, a tracking algorithm based on random finite set was proposed. Random finite set is a theoretically unified framework of optimal Bayesian multitarget tracking filter, but the recursion of posterior joint multitarget distribution is not practical in use due to the computational hurdle. Probability Hypothesis Density(PHD) is the first moment of multitarget posterior distribution, and the PHD filter is the suboptimal and practical alternative within the framework of random finite set. Sequential Monte Carlo method was proposed to propagate PHD. The target quantity was estimated by summing up all particle's weight. The kmeans method was adopted to cluster PHD to estimate the target states. Scenario simulation was set up, where the algorithm was tested under the conditions of different handover tracking tasks，false alarm rates and target numbers. Simulation results show that, the algorithm can simultaneously track the numbers and states of the targets among midcourse ballistic target group on spacebased IRFPA. 

Abstract:A new implementation method of simplex growing algorithm (SGA) is proposed based on support vector machine (SVM), which is free of dimensional reduction and makes use of distance measure instead of volume one. The unmixing equality of linear SVM and linear spectral mixing modeling (LSMM) is proved. The superiorities of linear SVM based spectral unmixing in two extended applications, combined use of endmember informations and nonlinearity use of the model, are explored. Experiments show that the computational complexity of the SVM based implementation method of SGA is decreased greatly, while the unmixing accuracy is obviously improved.

Abstract:To explore the effectiveness of TemperatureVegetation Angel Index in forecasting crop yield with MODIS, winter wheat yield forecast was taken as an example in Shijiazhuang and Xingtai city, Hebei province of China. Firstly, according to winter wheat biological characteristic, the four parameters of normalized difference vegetation index (NDVI), enhanced vegetation index (EVI), temperaturevegetation angel index (TVA) and enhanced temperaturevegetation angel index (ETVA) were calculated in heading stage. Secondly, the regressive models between groundbased measurements of winter wheat yield and NDVI, EVI, TVA and ETVA data from MODIS were established. It was found that there was significantly linear regressive relationship between yield and NDVI, EVI, TVA and ETVA. The correlation coefficient R2 between yield and NDVI, EVI, TVA and ETVA were 0.61、0.65、0.68 and 0.74, respectively. The models based on TVA and ETVA were better than that based on NDVI and EVI, especially the ETVA. This research shows that TVA/ETVA, which integrated vegetation index and land surface temperature, can be applied in yield forecast with improved forecast accuracy.