多波段偏振CCD相机的辐射定标研究

简要介绍了多波段偏振CCD相机系统。从分析面阵CCD探测器的光电响应不均匀性和三偏振方向光电响应的不一致性出发,介绍了基于辐射定标方法解决不一致性问题,得到辐射校正系数,提高了成像偏振信息的解析精度。     

光栅分振幅光偏振测量系统的研制

使用一个既能产生反射光衍射又能产生透射光衍射的特殊金属光栅作为分光器,研制一种新颖的高速光波偏振态测量系统。它没有使用转动光学部件或调制器,而是将金属光栅产生的四条1级衍射光的光强线性地转换为电信号,通过定标方法得到系统的非奇异的仪器矩阵,然后通过线性运算得到入射光的待测Stokes矢量。该系统结构紧凑、安装方便,可用作实时偏振测量术和椭偏测量术中的偏振态探测器。     

新型偏振特性因子及其传递关系的研究

偏振遥感图像通常可以采用强度、偏振度、偏振角或HIS柱形彩色空间表征目标偏振特性.本文通过建立光束在多层介质中传递的简单模型,找到一种新型偏振特性因子.此偏振特性因子所成图像是偏振度图像和偏振角图像信息复合的结果,其实质反映了偏振光束中的线偏振光的光强相对含量及它的偏振角方向.对伪装过的车牌进行偏振成像,实验表明此偏振特性因子可以用于特定环境下的伪装辨别.     

基于AOTF的高光谱偏振成像系统设计

为获得目标和场景的偏振信息,提高目标识别和地物探测的准确度,设计了基于液晶相位可变延迟器(LCVR)和声光可调滤波器(AOTF)的高光谱偏振成像探测系统。首先介绍了偏振成像探测的原理,然后给出了探测系统的结构,并对其光学系统的各元件进行了合理的参数分配,最后利用编制的信息处理软件对系统采集的高光谱偏振图像进行了处理,处理结果能够反映出目标的光谱特性和偏振特性,对于复杂背景下的目标探测与识别具有重要的应用价值。     

大面积有机半导体二维单晶膜偏振光电探测器件

偏振光电探测器件具有对光场矢量方向的探测能力, 可极大地丰富光电探测的信息维度, 揭露传统探测方法中所不能发现的隐藏信息, 因而在目标探测、地质遥感、机器视觉等方面具有重要的应用价值.利用材料结构的本征各向异性实现偏振响应, 有助于规避传统偏振探测需要耦合光学元件所导致的结构复杂和系统庞大等问题, 有助于实现器件的小型...     

利用挤压光纤双折射效应的自适应偏振控制器

报导了利用光纤应力双折射效应研制的1．55μm波长的自适应偏振控制 器,该控制器具有自动搜索、跟踪和精确控制光纤输出偏振态的功能。经初步检测,当偏振态变化3π/s时,输出偏振光强度为给定偏振方向分量总光强的92％,平均偏差小于2％。     

大数值孔径下的偏振成像分析

光刻设备的分辨率越来越高,以满足集成电路特征尺寸不断缩小的要求.根据瑞利判据,可以通过缩小曝光波长和工艺因子、增大数值孔径来提升光学投影光刻的分辨率.随着数值孔径的增加,光的偏振特性对成像的影响越来越大.通过分析偏振光的成像特性,控制照明的偏振方向,可以延伸光刻的分辨率.运用光的干涉原理分析了偏振光影响成像质量的原因,...     

亚波长金属光栅偏振器设计

针对仿生微纳导航传感器敏感波段380～520nm的要求，基于严格耦合波理论，设计了一种适用于蓝紫光波段的金属光栅偏振器，并应用等效介质理论直观地分析了金属光栅偏振器的工作原理．所设计的金属光栅偏振器与传统的金属光栅偏振器的不同之处在于：在基底和金属线栅之间增加了氟化镁薄膜，并且刻蚀一部分氟化镁薄膜．在垂直入射条件下，在整个可见光波段，金属光栅偏振器TN透射效率大于61．5％，消光比大于370；数值计算和理论分析表明，所设计的金属光栅偏振器是一种宽带宽、高TN透射效率和高消光比的偏振器件．     

偏振激光照明对多层薄膜结构成像对比度影响

光学多层干涉断层扫描技术(Optical multilayer interference tomography,OMLIT)应用于光电关联显微镜中以实现清晰的光学大视场成像，为高分辨率电镜图像提供目标区域标定。为了进一步提升成像对比度和定位精度，将偏振照明和OMLIT成像技术相结合，提出一种多层薄膜偏振照明的理论模型，使用矩阵传输方法对不同入射角的偏振光在不同材质、厚度的多层薄膜介质间的传播及干涉成像进行了仿真。结果表明，当照明光的电场振荡方向平行于入射面时，能够获得比非偏振光更高的图像对比度。当照明光以62°入射角照射金属银镀层样品表面，成像对比度提升高达138倍。这项工作为偏振照明OMLIT提供了理论基础，为光电融合显微成像技术的发展提供了全新的技术方案。     

一种新颖的偏振不敏感的阵列波导光栅

提出了一种新颖偏振不敏感的阵列波导光栅(AWG)。器件的输入端增加了一个全光学偏振自动控制器(AOPSC),可将注入AWG的随机偏振的输入光转换为与AWG中TE0模偏振方向相同且功率损耗很小的线偏振光。AWG结构设计采用非对称的平面波导,包层与波导芯层的相对折射率差为0.7%,波导芯层的宽厚比要高,可以消除TE与TM模的简并,使波导中只能激励TE0模,而使TM0模截止。这种AWG结构完全消除了不同偏振态信号光对AWG工作性能的影响,从而使器件对偏振不敏感。设计的8×0.8nm器件整体尺寸为2cm×1cm,串扰优于-30dB,最大插入损耗为4.2dB。     

基于p-Se/Al2O3/n-ZnO纳米棒阵列异质结的自驱动紫外-可见光探测器

自驱动光探测器能够在无外加偏压的情况下将光信号转化为电信号, 在工业和军事领域有着广泛的应用。本研究报道了p型Se薄膜和n型ZnO纳米棒阵列异质结的可控合成以及它们作为自驱动紫外-可见光探测器的应用。由于在ZnO和Se的界面处形成的内建电场将光生电子-空穴对分离, 促使它们向相反方向传输, 最终被电极收集, 在0偏压下获得了较高的光电流(435 pA), 从而实现无线的自驱动光电探测。并且, 在Se和ZnO界面处沉积的Al₂O₃层有效降低了暗电流。最终, 此器件在500 nm的单色光下显示了高响应率55 μA·W ^-1和大比探测率5×10 ¹⁰Jones, 并表现出了极快的响应速度(上升时间0.9 ms, 衰减时间0.3 ms)。     

Multispectral and Circular Polarization-Sensitive Carbon Dot-Polydiacetylene Capacitive Photodetector (Small 31/2023)

Multispectral photodetectors (MSPs) and circularly polarized light (CPL) sensors are important in opto-electronics, photonics, and imaging. A capacitive photodetector consisting of an interdigitated electrode coated with carbon dot/anthraquinone-polydiacetylene is constructed. Photoexcitation of the carbon dots induces transient electron transfer to the anthraquinone moieties, and concomitant change in the film dielectric constant and recorded capacitance. This unique photodetection mechanism furnishes wavelength selectivity that is solely determined by the absorbance of the carbon dots incorporated in the anthraquinone-polydiacetylene matrix. Accordingly, employing an array of polymerized-anthraquinone photodetector films comprising carbon dots (C-dots) exhibiting different excitation wavelengths yielded optical “capacitive fingerprints” in a broad spectral range (350–650 nm). Furthermore, circular light polarization selectivity is achieved through chiral polymerization of the polydiacetylene framework. The carbon dot/anthraquinone-polydiacetylene capacitive photodetector features rapid photo-response, high fidelity, and recyclability as the redox reactions of anthraquinone are fully reversible. The carbon dot/anthraquinone-polydiacetylene platform is inexpensive, easy to fabricate, and consists of environmentally friendly materials.     

Thermally stable Pd/Sn and Pd/Sn/Au ohmic contacts to n-type GaAs

Thermal stability of novel Pd/Sn and Pd/Sn/Au Ohmic contacts to n-GaAs has been investigated and compared to the non-alloyed Pd/Ge and alloyed Au–Ge/Ni metallizations. Metallization samples are furnace annealed at various temperatures and systematically characterized utilizing Scanning Electron Microscopy (SEM) and current–voltage (I–V) measurements. Contact resistivities, ρ_c, of the proposed metallization are measured using a conventional Transmission Line Model (cTLM) method. The Pd/Sn Ohmic contacts display superior thermal stability at 410°C when compared to the Pd/Ge contacts. After annealing at 410°C for 4 h, ρ_c of the Pd(50 nm)/Sn(125 nm) metallization remains in the low 10⁻⁵ Ω cm² range, whereas ρ_c values increase to 10⁻⁴ Ω cm² for the Pd(50 nm)/Ge(126 nm) contacts. At 410°C, the Pd/Sn/Au metallizations also display better thermal stability than that of non-alloyed Pd/Ge and alloyed Au–Ge/Ni metallizations. The long-term stability at 300°C of the Pd/Sn and Pd/Sn/Au Ohmic contacts is also reported.     

Titania-germanium nanocomposite for photo-thermo-electric application

The introduction of germanium (Ge) into titania (TiO(2)) creates an attractive semiconductor. The new semiconductor is named titania-germanium (TiO(2)-Ge). Ge dots are dispersed in the distorted TiO(2) matrix of TiO(2)-Ge. The quantum Bohr radius of Ge is 24.3?nm, and hence the properties of the Ge dot can be varied by tailoring its size if it is smaller than its Bohr radius due to the quantum confinement effect (QCE). Therefore, simply by changing the Ge concentration, the morphology of TiO(2)-Ge can be varied within a wide range. Consequently, the optical, electronic and thermal properties of TiO(2)-Ge can be tailored. TiO(2)-Ge becomes a promising material for the next generation of photovoltaics as well as thermoelectric devices. It could also be used for photo-thermo-electric applications.     

Noise contributions for imaging spectrometers

In the past decade imaging spectrometers for observation of the Earth were developed to use the complete information of a spectrum as a major tool in the study of physical and biological processes of the Earth. Instead of a few relatively broad spectral bands (line detector), this imager concept provides for the detection of many contiguous narrow spectral bands by applying the technology of matrix detectors. The change from one-dimensional to two-dimensional solid-state imagers makes it necessary to carry out the specific signal-to-noise ratio (SNR) analysis of such detectors. A simulation of maximum and minimum radiances for typical spectral signatures of the Earth (water, vegetation) and the verification of these radiances with modular optoelectronic scanner data provide the means for calculation of electrons generated at the matrix detector. For a hypothetical sensor, water-minimum and vegetation-maximum signals are calculated, and the degradation of the SNR caused by image smear of two-dimensional solid-state imagers is demonstrated.     

Object detection with a field-portable spectropolarimetric imager

A relatively compact, lightweight, and programmable spectropolarimetric imager was used to collect spectral and polarization data from various objects and backgrounds, both in the laboratory and in field tests. This imager uses a tellurium dioxide (TeO(2)) acousto-optic tunable filter and a liquid-crystal retardation plate with a CCD camera. The spectral images were collected 450-1000 nm at 10- or 20-nm intervals at two or four polarization settings for each spectral interval. We analyzed a portion of these data to assess the effectiveness of this system for object detection. We present our measurements and discuss the analysis results.     

Si-based tunable flattop photodetector with a stepped Fabry-Perot cavity

This paper presents the design and analysis of a Si-based tunable flattop photodetector realized by the introduction of a stepped Fabry-Perot cavity, which can be thermally tuned via applying tuning power on its tuning electrode. By using a transfer matrix method, the spectral response of the photodetector is simulated in detail, indicating a flattop line shape can be achieved with an optimum step height. A trade-off residing in this device between the free spectrum range and the ease of fabrication of step height is also revealed and analyzed. In the final design of the photodetector, 1 dB linewidth of 0.5 nm, 3 dB linewidth of 0.8 nm, 6 dB linewidth of 1.2 nm, peak quantum efficiency of 40%, tuning efficiency of 91 mW/nm are theoretically obtained. We discuss the epitaxial growth and fabrication of the photodetector in the end, exhibiting the mature technique available for this device.     

Generalized signal-to-noise ratio for spectral sensors with correlated bands

Traditional spectral sensors are intentionally designed to minimize overlap among spectral response functions of different bands. In contrast, some emerging classes of spectral sensors exhibit significant band overlap. An effect introduced by such band overlap is that the photodetector noise of one band is coupled into the others in subsequent data processing steps. Because of this, the traditional band-by-band definition of signal-to-noise ratio (SNR) cannot fully describe the detector's noise level. We devise a general definition of SNR in spectral space based on a recently developed geometrical spectral imaging model [J. Opt. Soc. Am. A24, 2864 (2007)]. With this model, we can find an orthogonal basis of the spectral response functions for the spectral sensor with decreasing instrument SNRs. We can also define the average instrument SNR for the whole sensor, which makes it possible to characterize quantitatively the photodetector noise of a spectral sensor with correlated bands.     

500℃下利用UHV/CVD在Si衬底上直接生长近平面Si0.5Ge0.5层

利用UHV/CVD系统,在一个相对较低的温度500℃下,研究了Si1-xGex层中的Ge含量与生长条件之间的关系,此时的Si1-xGex层处于一种亚稳的状态.并直接在Si衬底上生长制备了10个周期的3.0 nm-Si0.5Ge0.5/3.4 nm-Si多量子阱.拉曼谱、高分辨显微电镜和光荧光谱对其结构和光学性能进行的表征表明这种相对较厚的Si0.5Ge0.5/Si多量子阱结构基本上仍是近平面生长的,内部没有位错,其在电学和光学器件上具有潜在的应用.     

A Highly Responsive Organic Image Sensor Based on a Two‐Terminal Organic Photodetector with Photomultiplication

Highly responsive organic image sensors are crucial for medical imaging applications. To enhance the pixelwise photoresponse in an organic image sensor, the integration of an organic photodetector with amplifiers, or the use of a highly responsive organic photodetector without an additional amplifying component, is required. The use of vertically stacked, two‐terminal organic photodetectors with photomultiplication is a promising approach for highly responsive organic image sensors owing to their simple two‐terminal structure and intrinsically large responsivity. However, there are no demonstrations of an imaging sensor array using organic photomultiplication photodetectors. The main obstacle to a sensor array is the weak‐light sensitivity, which is limited by a relatively large dark current. Herein, a highly responsive organic image sensor based on monolithic, vertically stacked two‐terminal pixels is presented. This is achieved using pixels of a vertically stacked diode‐type organic photodetector with photomultiplication. Furthermore, applying an optimized injection electrode and additionally stacked rectifying layers, this two‐terminal device simultaneously demonstrates a high responsivity (>40 A W^?1), low dark current, and high rectification under illumination. An organic image sensor based on this device with an extremely simple architecture exhibits a high pixel photoresponse, demonstrating a weak‐light imaging capability even at 1 µW cm^?2.