Abstract:GaAs-based 1.3 μm InAs quantum dot laser have been grown by MBE system. Under the optimized InAs quantum dots growth temperature of 520℃， and the methods of Be-doping in the active region are adopted for better device performance. With a ridge width of 100 μm and cavity length of 2 mm， the maximum output power of single facet without coating has reached up to 1008 mW under continuous wave （CW） operation at room temperature， and the threshold current density is 110 A/cm². The QD lasers can still operate at continuous waves （CW） up to 80℃， and the characteristic temperature below 50℃ is as high as 405 K.

Abstract:Based on the first principles study, this paper investigates the control of the optical properties of GaN（0001） surface by metal atoms. The work was conducted with different kinds of metals （Ni, Ru, and Au） that are commonly used in experiments. The results show that charge transfer occurs from adatoms to GaN（0001） surface,and the work function of GaN（0001） surface is reduced by Ni and Ru adsorption. The impurity energy levels are introduced to the band gap of GaN（0001） surface, resulting in the reduction of barrier height of carrier transition, the optical properties are then modulated. The red shift of main peaks in the low photon energy region for all the optical parameters and the shrinkage phenomenon of all the optical curves in the high photon energy region are observed, the numbers and positions of characteristic peaks in all the optical curves change significantly. Furthermore, the absorption of GaN（0001） surface to visible light and even infrared light is enhanced after the adsorption of metal atoms, which is suitable for the longer wave light detection instead of UV detection.

Abstract:Mn_1.56Co_0.96Ni_0.48O₄ （MCNO） thin films with spinel structure were grown on YSZ （100） substrates at different deposition temperatures from 500℃ to 700℃ by pulsed laser deposition. Since the deposition temperature is an important factor in fabricating high-quality films， the structural， electrical and magnetic properties of MCNO thin films as a function of deposition temperature are investigated. By analyzing the X-ray diffraction patterns and the atomic force microscopy images， it is discovered that the crystallization of MCNO films is highly dependent on the deposition temperature. With the increasing deposition temperature， the resistivity of MCNO thin films is a change of V-type， and the electrical conduction of the MCNO films is controlled by a small polaron hopping mechanism. Meanwhile， the temperature-dependent magnetization curve reveals that all the samples show ferromagnetism to paramagnetism transition and the MCNO film deposited at 600℃ has a high Curie temperature of 216 K. All the results above demonstrate that MCNO film deposited at 600℃ has satisfactory performance， which is desirable for applications of thermistor devices and multifunctional heterojunctions.

Abstract:The Spin-orbit coupling interaction, Zeeman effect and interface microroughness effect in an HgCdTe inversion layer were investigated by experimental measurement. Theoretical models were used to analyze the weak antilocalization (WAL) at different temperatures and in different in-plane magnetic fields. It is found that both the Zeeman effect and the interface microroughness effect will suppress the WAL. And the interface microroughness effect takes effect by facilitating a weak localization in the normal direction of the two-dimensional electron gas (2DEG) plane. With the increasing magnetic field, the interface microroughness induced WL will be suppressed first and then the WAL will be suppressed by Zeeman effect. What’s more, the analysis of parameters τ?τ_? and |m_r^* g_3^* | indicates that the Zeeman effect’s suppression on WAL is independent ofdoes not depend on temperature.

Abstract:The swallow-tailed defect is a typical defect in MBE HgCdTe which has a uniform and regular shape. The morphology， structure and growth mechanism of swallow-tailed defect were investigated. Two raised swallow-tails are major characteristic on the surface， and an inverted pyramid structure surrounded by （1-1-1），（-1-11），（1-11），（-1-1-1）and （211） crystal faces is demonstrated in the film of the defect. The swallow-tailed defect is （552）A twin defect， the difference of growth rate between （552）A twin crystal and （211）A matrix is the root cause of defect formation. The nucleation sites and growth planes of （552）A twin crystal， （-1-11） and （1-11）crystal plane， which determine the morphology and structure of swallow-tailed defect， depend on different Schmid factor of 12 slip systems in HgCdTe.

Abstract:A polarization-maintaining hollow-core negative curvature fiber is proposed， which can be used to transmit mid-infrared laser with an operating wavelength of 2.94 μm. By adjusting the thickness of the cladding tube in the y-direction and the maximum distance from the nested tube to the inner diameter of the cladding tube， the polarization mode in the y-direction is weakly coupled with the surface mode of the cladding tube. By optimizing the core diameter and the outer diameter of the cladding tube， the y-direction polarization mode is strongly coupled with the cladding tube surface mode， causing the y-direction polarization mode to leak out of the core. The gap between the cladding tubes guides the high-order mode to leak out of the core， while the x-direction polarization mode keeps the low confinement loss due to the coupling suppression effect of the thickness of the cladding tube and the nested tube. Finally， a polarization-maintaining hollow core negative curvature fiber with an operating wavelength of 2.94 μm is obtained. The confinement loss of the x-direction polarization mode is 2.8×10^-2 dB/m， the polarization extinction ratio is greater than 2×10³， the high-order mode rejection ratio is greater than 100， and the birefringence is1.4×10^-5. When bending in the y direction with a radius of 25 cm， the bend loss is 0.62 dB/m.

Abstract:A D-band（110~170 GHz） direct detection radiometer front-end which consists of detector module， low noise amplifier module and standard gain horn antenna. The D-band detector is designed and fabricated based on zero-bias Schottky barrier diode HSCH-9161 and the measurement shows that the voltage sensitivity is larger than 400 mV/mW between 110~140 GHz， larger than 120 mV/mW in D-band and the maximal value reaches about 1 600 mV/mW@110 GHz. The D-band LNA module is packaged with self-designed MMIC and the module measurement shows the peak gain is 10.8 dB@139 GHz， the gain higher than 7.8 dB from 137 GHz to 144 GHz， the measured input return loss （S11） and output return loss （S22） are better than -5 dB and 8.5 dB in operating frequencies， respectively. Finally， the imaging experiments based on this front-end are carried out.

Abstract:Millimeter wave (mmW) multiple-input multiple-output (MIMO) radar is state-of-the-art technique for security imaging. However, the exploitation of large number of transmit/receive channels leads to much higher cost and complexity for the MIMO radar than that of the single-channel radars. Aiming for developing the low-cost and low-complexity mmW MIMO security imaging radar, dual-code-division-multiplex (dual-CDM) technique has been proposed in this paper. It is worth noting that the proposed method can realize the similar imaging performance with the traditional multi-channel MIMO radar by a single transmit /receive channel, which is of great significance for the development and application in the area of security imaging. Moreover, the de-multiplex code, which can attain the maximum code diversity gain against the interference, is designed based on mismatched filter theory. Finally, both the numerical and the experimental results are provided to verify the correctness and the validity of the proposed methods, which shows that quite a satisfactory imaging performance is achieved.

Abstract:Aiming at the requirement of feasibility analysis for ice cloud detection by space borne cloud radar， the single scattering characteristics of non-spherical ice crystals to 340 GHz electromagnetic wave were analyzed， then the echo characteristics of non-spherical ice crystal cloud and dual wavelength ratio （DWR） of 94 \ 340 GHz cloud radars were studied based on different volume scattering models， while the variation of DWR with altitude and the thickness of ice clouds that can be penetrated were discussed assuming the vertical distribution of ice clouds. Compared with 94 GHz and 220 GHz， the scattering ability of ice particles to 340 GHz electromagnetic wave is enhanced， but at the same time， the attenuation by clouds is also greatly increased， and the attenuation coefficient of ice clouds to 340 GHz wave is about 5-130 times that to 94 GHz wave. The 340 GHz cloud radar can detect the shallow ice clouds with low ice water content （IWC）， that is， ice cloud with thickness of 2 km and IWC of 0.0001～0.2 g/m³ can be detected basically， and the electromagnetic wave penetration ability is greatly reduced due to the attenuation of thick clouds with more water content， when the maximum IWC reaches 1 g / m³ in the condition of the assumed vertical distribution of IWC， about more than 40% of cloud thickness for ice clouds within 5 km will be detected. Attenuation also results in different DWR for clouds with the same drop spectrum at different heights. The value and vertical distribution of IWC affect the value of DWR and the thickness of the clouds detected by electromagnetic wave. The attenuation increases with the increase of IWC and the electromagnetic wave attenuation of high frequency cloud radars is larger， that make the DWR larger， so the DWR is related to the number concentration of the spectrum. As a result， the attenuation correction is very important when using DWR retrieval.

Abstract:A stepped frequency imaging radar which based on 0.22 THz high-power gyrotron oscillator was designed. The dual Cassegrain antenna with separate transceiver was used for transmitting stepped frequency pulse signal. Frequency adjustment of gyrotron oscillator was achieved by adjusting gyrotron electron beam voltage or superconducting magnet strength. The design schemes for imaging radar were given， the radar detected range and high-resolution range profile of the stepped frequency radar system were analyzed， and inverse synthetic aperture radar （ISAR） imaging simulation was carried out. The results of theoretical calculation and simulation show that the radar could detect the target with scattering area of 0.01 m² by 1.982 km and distinguish the targets with a distance of 2 cm at 500 m. The radar can be used for investigations on target recognition of small objects such as UAV which can take concealed weapons and threat material.

Abstract:A multi-band tunable terahertz metamaterial absorber is proposed. In the structure of the metamaterial absorber， a photosensitive semiconductor silicon material was added and designed a special top metal resonator， analyzed the influence of the parameters such as the opening length， line width and dielectric layer thickness on the absorption spectral characteristics of the terahertz metamaterial absorber. According to the relationship between illumination and the conductivity of photosensitive semiconductor silicon， studied the frequency tuning characteristics of the terahertz metamaterial absorber. The simulation results obtain 12 absorption frequency modulations in the terahertz band， the absorption rate of 10 absorption peaks of them exceeds 90% near perfect absorption， and 6 absorptions rate up to 99% perfect absorption. Moreover， the absorptivity modulation depth and relative bandwidth reaches 85.9% and 85.5% respectively， with strong tunable characteristics. The photo excited terahertz metamaterial absorber has a simple structure， multi-band tunable and perfect absorption characteristics， and expands the application range of the absorber.

Abstract:The high-pressure absorption spectrum at 6046.96 cm^-1 of methane was obtained with the measurement experimental platform. The empirical mode decomposition algorithm was used to filter out the detection noise caused by window deformation at high-pressure. Consequently， the overall root-mean-square error （RMSE） of absorbance signal was reduced by 3.87 times， and the residual error of absorbance signal fitting was lower than ±1% by using Lorentz line-type fitting algorithm. These studies showed that the absorption line width increased with the pressure increasing， and the mutual broadening coefficient of nitrogen-methane molecules at high-pressure was calculated as 0.0631 cm ^-1atm ^-1. Moreover， the absorption line appeared a "red shift" phenomenon as the pressure increasing， and the pressure shift coefficient of nitrogen-induced was calculated as -0.00848 cm ^-1atm ^-1. Therefore， a method of concentration inversion at high pressure was proposed by the linear relationship between the detection wavelength， pressure， and pressure shift coefficient. In conclusion， the research on spectrum broadening characteristics in high-pressure environment lays foundation for spectrum detecting in industrial environment.

Abstract:This paper presents an automatic approach for measurement of the superficial spreading depth of cutaneous melanomas based on microscopic hyperspectral imaging technology. To extract the skin granular layer， an edge detection method combined with kernel minimum noise fraction is proposed. Then least squares support vector machine based on characteristic spectrum supervision is used to identify malignant melanocytes. The measurement of tumor superficial spreading depth depends on the vertical distance from the skin granular layer to the deepest malignant melanocytes. Experimental results illustrate that the proposed method is possible to provide an effective reference for the diagnosis and treatment of cutaneous melanoma.

Abstract:Currently the FY-4A/GIIRS data assimilation directly uses the cloud detection product from Advanced Geostationary Radiometric Imager （AGRI）， and the whole channel data should be removed when the corresponding IFOV is contaminated by cloud， leading to the loss of some available channel information. In order to improve the utilization rate of those data， a cloud detection algorithm is set up with GIIRS observation and RTTOV simulation by adopting the method given by McNally， together with radiation characteristics such as GIIRS sensitivity. The results of the proposed method are generally identical to those from the AGRI CLMs， where some minor differences will occur for IFOVs with a certain of broken clouds. Using the derived the heights of cloud top for each IFOV， the clear channels with respect to the cloud IFOVs can be identified with the data utilization increased by around 13.76% in statistics. This proposed cloud detection algorithm can provide an important reference for GIIRS data assimilation.

Abstract:In this paper， we introduced the unique advantages of the thermal infrared hyperspectral imaging in many applications， and then discuss the design to optimize sensitivity of the airborne thermal-infrared hyperspectral imaging system （ATHIS）. Additionally， we establish emission spectrum of laboratory minerals and build the radiation model to measure the absorption spectrum of gas， with which the procession of separation of spectrum and temperature is analyzed. Finally， ATHIS is used to carry out laboratory measurements of mineral emission spectrum and gas infrared absorption spectrum. The results show that the data method we proposed for ATHIS can accurately invert mineral emissivity spectrum and gas absorption spectrum. In the future， ATHIS will be used to carry out multi-platform remote sensing application experiments， which will lay the foundation for future development of space-borne thermal infrared hyperspectral camera and data processing methods.

Abstract:Based on the satellite laser ranging （SLR） system at Shanghai Astronomical Observatory， the laser output energy was increased by using the 885 nm end-pumped Nd：YAG amplification. Each pulse of 10 kHz was obtained near-equal amplitude by controlling the pump gain current， Nd：YAG crystal cool water temperature and building time of regeneration amplification. An average power of 6 W picosecond laser in a wavelength of 532 nm was obtained at a repetition rate of 10 kHz with the divergence angle of 0.6 mrad， pulse width of 30 ps， a beam quality M² of 1.2. The noise levels for single photon detector at each repetition rate of 1 kHz， 2 kHz， 4 kHz， 5 kHz， 6.25 kHz， and 10 kHz was measured and analyzed respectively. The relationship between the false alarm probability and the ranging gating is obtained. The relationship between the number （N） of noise photons and the repetition rate （f） is， and the relationship between the false alarm detection probability （P） and the ranging gated （Δt） at the repetition rate of 10 kHz is ， and also the function of the number of laser echoes with noise， laser energy and repetition are obtained， which is beneficial to design the SLR system. Therefore， it realizes the satellite laser ranging in all day， and the farthest distance was to the synchronous orbit of Beidou Compassi6b satellite.

Abstract:The output characteristics of passively Q-switched YVO₄ Raman laser derived by a diode end-pumped Nd:YAP laser at 1080 nm was investigated. A Cr⁴⁺:YAG/YAG composite crystal with an initial transmittance of 85% was used as saturable absorber. The first-Stokes wave output power and pulse characteristics based on a-cut YVO₄ crystal with the Raman shift of 890 cm^-1 were studied. Under an incident pump power of 9.87 W, the average output power of 0.76W and conversion efficiency of 7.7% were obtained for the first-Stokes wave. The pulse repetition frequency rose from 3.7 to 33.5 kHz as the incident pump power increased from threshold to 9.87 W. The pulse width was about 1.5 ns at the maximum incident pump power. Therefore, the corresponding maximum single pulse energy and peak power were 22.8 μJ and 15.2 kW, respectively.

Abstract:A remote sensing camera needs a thin-film filter with visible （wavelength 500~720 nm） and near infrared （wavelength （1064±1） nm） dual band-pass spectrum channels at any same geometric position. The spectrum and transmission of the two channels need was modulated accurately. JGS-1 fused quartz was used as the substrate， Ta₂O₅ and SiO₂ thin film was used as high （H） and low （L） reflective index layers respectively. 52 and 88 layers deposited on the two surfaces of substrate by dual ion beam sputtering method. The average transmission of 500~720 nm band reaches 92%， and the peak transmission of （1 064±1） nm band controlled in（26±1）% range.

Abstract:The body infrared radiation characteristics are related to physiological activities such as respiration. We developed a novel approach to remotely monitor respiration by using the time-series infrared thermography of face. To improve the accuracy and robustness， the algorithm is researched based on Harris corner detection and optical flow field tracking method， which enhance the accuracy of the nostril region tracking. We demonstrate the approach by monitoring the respiratory of human in different environment and evaluating its time-frequency characteristics and statistical parameters. The results show that the approach can reliably monitor the real-time respiration and its pattern. That would be helpful for the clinical application of the infrared thermography on monitoring physiological status.

Abstract:The moon is observed at a specific time in the cold space reference sampling area of the visible infrared radiometer （VIRR） of FY-3 meteorological satellite， which makes the remote sensing image appear abnormal area of strip image with reduced or even no code value in the earth region at that time， which has an impact on the remote sensing data. Based on the characteristics of VIRR orbit operation， on orbit working mode and cold space data sampling mechanism， this paper analyzes the reasons why the moon is observed in the cold space sampling area of VIRR and affects the remote sensing data. The mechanism of registration dislocation between lunar image channels caused by the rotation of VIRR scanning image in cold space sampling is expounded. The time and regularity of this phenomenon in one year period are calculated by satellite orbit simulation. The processing suggestions for the affected remote sensing data are put forward. The preliminary attempt of data correction is made and the possibility of data correction is analyzed.

Abstract:To ensure the fusion quality and efficiency simultaneously， a novel image fusion method based on multi-scale Gaussian filtering and morphological transform is proposed. The multi-scale Gaussian filtering is designed to decompose the source images into a series of detail images and approximation images. The multi-scale top- and bottom-hat decompositions are used respectively to fully extract the bright and dark details of different scales in each approximation image. The multi-scale morphological inner- and outer-boundary decompositions are constructed to fully extract boundary information in each detail image. Experimental results demonstrate that the proposed method is comparable to or even better in comparison with typical multi-scale decomposition-based fusion methods. Additionally， the method operates much faster than some advanced multi-scale decomposition-based methods like NSCT and NSST.

Abstract:In order to expand application of uncooled short wave infrared array detectors for low-light night vision， a research on low-light imaging of short-wave infrared have carried out. This paper proposes a new image enhancement method to suppress image noise， enhance image details and improve image quality. The proposed schemes use 3DNR （3D noise reduction）， combine the multi-scale Gaussian differential method with the edge preserving filter to separate the high-frequency information and hidden noise of the image to the maximum extent， and then carry out the adaptive grayscale mapping for the image. The experimental results demonstrate that the proposed algorithm outperforms some state-of-the-art algorithms， and it can achieve outstanding image enhancement performance and suppress the time-domain noise of the image under low-light illumination.