Outlook on quantum dot infrared photodetectors

This paper reviews the present status and gives outlook on future developments of quantum dot infrared photodetectors (QDIPs). At the beginning the paper summarizes the fundamental properties of QDIPs. Next, an emphasize is put on their potential developments. Investigations of the performance of QDIPs as compared to other types of infrared photodetectors are presented. A model is based on fundamental performance limitations enabling a direct comparison between different infrared material technologies. It is assumed that the performance is due to thermal generation in the active detector’s region. In comparative studies, the HgCdTe photodiodes, quantum well infrared photodetectors (QWIPs), type II superllatice photodiodes, Schottky barrier photoemissive detectors, doped silicon detectors, and high temperature superconductor detectors are considered. Theoretical predictions indicate that only type II superlattice photodiodes and QDIPs are expected to compete with HgCdTe photodiodes. QDIPs theoretically have several advantages compared with QWIPs including the normal incidence response, lower dark current, higher operating temperature, higher responsivity and detectivity. The operating temperature for HgCdTe detectors is higher than for other types of photon detectors.     

Improving injection efficiency of gate modulation ROIC interface for HgCdTe IR photodiodes

Microsystem Technologies - A new interface circuit for readout of HgCdTe Infrared photodiodes is proposed that can be used for efficient transfer of photocurrent from the photodiodes to the...     

An improved source follower per detector ROIC for HgCdTe infrared photodiodes

Microsystem Technologies - A new readout circuit for HgCdTe based Infrared photodiodes has been proposed. In this work, the conventional source follower per detector (SFD) architecture of the...     

Line integration HgCdTe focal plane array

Line integration 384 × 288 Focal Plane Array (FPA) consists of HgCdTe (MCT) photodiodes array formed in the mercury cadmium telluride p-type epitaxial layers grown both by liquid phase epitaxy (LPE) or molecular beam epitaxy (MBE). Grown by these methods MCT layers have multilayer compound structure. Silicon readout integration circuit (ROIC) performs the photocurrents integration during one line signals output (one row of pixels) period, and signals multiplexing in two output channels from the focal plane. The photodiodes array pitch in each direction is 28 μm. The influence of MCT surface irregularities and imperfections of MCT epitaxial layers on number of defective elements is investigated. The text was submitted by the authors in English.     

Disruptive infrared image sensors enabled by quantum dots

Sensors based on quantum dot photodiodes promise quality and accessibility improvement of infrared imaging. We demonstrate miniaturization by sub-2-μm pixel pitch arrays. Functionality is confirmed with external quantum efficiencies above 40% at 1450 nm. Monolithic integration enables high throughput and wide deployment of short-wave infrared (SWIR) imagers in applications that previously could not afford them.     

被动FTIR遥感技术的微弱信号调理电路设计

微弱信号调理电路设计的好坏直接影响到被动傅里叶变换红外光谱仪(FTIR)的探测精度。基于HgCdTe光电导型红外探测器接受干涉光后输出的微弱电信号来设计前置检测电路和放大电路,该电路具有高增益、高信噪比、相位补偿功能,有效降低了噪声和温漂以及大的动态输入范围等特性。红外探测器将干涉红外光转换为10-8mA数量级的微弱电信号,在此输入条件下对信号调理电路进行实测,试验结果表明,该电路测量精度高,具有较好的稳定性,且结构简单易实现,可以在光谱仪应用中验证其正确性和可行性。     

硅光电二极管结构特性研究

为探讨光电二极管工作机理及其改进潜力,从一款常规光电二极管应用产品的设计入手,采用光敏区尺寸逐渐变大、呈规律性排列的硅光电二级管串联的结构,分析其特性与机理.在此基础上对同类产品进行优化,详细阐述新结构工艺原理与实现方式,分别从器件结构、工作原理、不同结构的优劣点等方面对比改进前后两种不同结构光电二极管的特性.从工艺参...     

CMOS X-rays detector array based on scintillating light guides

This paper describes a pixel imaging array consisting in 400 μm×400 μm photodiodes fabricated in CMOS technology. An array of scintillating CsI:Tl crystals is placed above the photodiodes. These crystals are encapsulated in aluminum walls, forming a light path that guides the visible light produced by the scintillating crystal into the photodiodes. In this way, the X-ray energy is first converted into visible light which is then detected by the photodiode at the end of each light guide. The scintillator is 800 μm thick, absorbing almost all 20 keV X-ray photons. Usually, the spatial resolution of the scintillating X-ray detectors is identical to the scintillator thickness. By using the light guides, the scintillator thickness can be increased without decreasing the spatial resolution. The increase of the scintillator thickness is desirable in order to increase the X-rays absorption efficiency. Tests carried out on the system show very promising results near 20 keV.     

Modified photo-sensors for grating-image type micro-encoder

New integration technique for grating-imaging-type encoder is proposed and the sensor for the encoder has been fabricated using Si micromachining technology. The sensor consists of the Si grids and line photodiodes. The light emission through the Si grids and the light detection with the four-phase-shifted line photodiodes make the optical system compact. Moreover, another photodiode array of the M-series arrangement is installed on the same substrate for the zero-point detection.     

末制导炮弹中的目标探测传感器技术

分析了末制导炮弹中常用的两种目标探测器（红外传感器和激光传感器）的特点及工作原理，介绍了激光传感器（由光敏二极管组成）在末制导炮弹中的具体运用。     

HgCdTe焦平面探测器热应力有限元分析

为降低HgCdTe焦平面探测器的内热应力、提高其可靠性,在MSC Patran和MSC Nastran 中对HgCdTe焦平面探测器进行热-力耦合分析.借助MSC Patran的参数化建模方法建立焦平面探测器的有限元模型,对该模型进行热分析,将结果作为温度载荷进行静力分析,得出HgCdTe芯片热应力分布情况.通过分析5...     

太阳位置光电模拟信号检测跟踪的实现

本文介绍了对放置在检测板上的4个光电二极管,在太阳光照射下,产生的电流信号进行模拟信号采集和单片机处理数据的实现过程。给出了基于单片机的模拟信号采集系统的总体框架,对硬件及软件设计作了详细的说明。系统以SPI为传输方式,以STC89C52为控制器,实现了信号的模数转换及数据的传送与处理。本文设计的光电模拟信号检测跟踪方案,更好的确定太阳辐射角度的精确位置,控制更精准。     

一种车窗防夹光纤传感系统

提出一种车窗防夹的多模光纤传感系统, 该系统安装在车窗框内,并基于斑纹图样的变化来获得信号.斑纹图样的变化被光电传感器阵列测量,其传感信号经过A/D转换器送进计算机内进行处理,然后,驱动车窗马达进行相应的动作.实验结果表明:该系统工作良好.     

Advanced optical methods for safe image reproduction on automotive displays

Modern cars are equipped with camera monitor systems (CMSs), such as a backup camera or side-mirror replacement. These systems are expected to perform optimally and achieve high safety levels (ASIL). Currently, only digital data are supervised in CMSs and safety mechanisms for such systems are individually derived on a case-by-case basis which is not effective. This study proposes generic optical supervision for displays of automotive CMS. This paper introduces “light-to-light” (camera to display output) protection for both in-car CMS and remote operator monitors used in autonomous car fleet operation centers. The first method is based on photodiodes attached to the display to optically supervise, for instance, the speedometer of vehicles. By combining intensities of photodiodes with calibration data, we can compare the measured speed with the value from CAN (Controller Area Network) data. The second method that entails capturing the display content using a camera enables top safety levels for both in-car displays and remote operator monitors. This safeguarding was successfully verified by conventional image processing and artificial intelligence (AI)-based analysis methods. Our results demonstrate that AI methods allow a substantial reduction in the wireless transmission bandwidth from a car to a remote operator compared with conventional image processing.     

A silicon integrated opto-electro-mechanical displacement sensor

This paper describes a compact and low cost micro-opto-electro-mechanical displacement sensor. Our purpose is the fabrication of a long range, nanometer resolved encoder using a standard CMOS technology, in order to integrate the optical metrology system (photodiodes, analog and digital circuits) on a single chip. We introduce the interferometric linear encoder principle using diffraction gratings; then we present results of optical and electrical characterization of an optoASIC including photodiodes and associated electronic integrated on a standard 0.6 μm CMOS process. This CMOS circuitry is then included inside of a prototype of linear displacement encoder using the principle of diffraction gratings in reflection. Finally, we present the fabrication of micrometer and sub-micrometer diffraction gratings etched in silicon material, in order to obtain a higher encoder integration.     

A contrast- and brightness-insensitive optoelectronic edge detector

A specialized photodetector structure for optical edge detection and its CMOS-compatible realization are presented. It can detect a single edge with a relative motion to the detector. Because of point symmetry, the edge may be detected regardless of its orientation. Influences of contrast and brightness variations at an edge can be eliminated by subtracting the photocurrents of two photodiodes arranged in a circle/ring structure. The detectors are fabricated in CMOS technology and have been successfully tested.     

Photoconductor‐based (direct) large‐area x‐ray imagers

Abstract— A brief overview of the present status of active‐matrix flat‐panel direct x‐ray imagers (D‐AMFPI) is given. The spatial resolutions of direct and indirect imagers are compared, and it is pointed out that the lack of light scattering greatly improves resolution. Furthermore, the resolution does not degrade as layers of the x‐ray detector materials become thicker for better x‐ray absorption at higher x‐ray energies, opposite to that of indirect imagers. Different direct x‐ray conversion materials are compared, how the physical properties influence the x‐ray detection efficiency, and imager stability are discussed. Ghosting and image‐lag properties are also weighted. A few x‐ray‐sensitive photoconductor materials produce very‐high x‐ray conversion efficiency, which could be advantageous for low‐dose fluoroscopy to overcome the noise of the readout electronics. Last, but not least, the manufacturing advantage of the direct imagers is emphasized. The direct imagers do not need p‐i‐n photodiodes, so the a‐Si TFT matrices for these arrays can be manufactured at any LCD manufacturing sites and not only at a few, very specialized companies where the p‐layers for the photodiodes can be deposited.     

A one-chip scanning retina with an integrated micromechanicalscanning actuator

A microsensor that merges sensing and scanning functions on a single chip has been designed and fabricated, resulting in the first integrated scanning retina of its kind. A microfabrication technique has been developed to combine a one-dimensional array of photodiodes and electrostatically driven scanning slits on a single chip. The scanner actuates 12-μm-wide microslits by up to 20 μm on top of 30-μm-wide photodiodes, and the motion generates an effect similar to that of the retinal scanning vergence found in the insects' compound eyes. The silicon retina is coupled with an array of 120-μm-diameter microlenses to compose a microsized scanning compound eye, and the effect of retinal scanning in edge and position detection is demonstrated with the sensor. Each individual visual unit of the compound eye detects light contrast due to the scanning motion of the visual axis. The architecture of this scanning retina increases the resolution of a visual system with a relatively small number of receptors     

光敏二极管温度特性的简易测量方法

为了保证光纤传感器的长期工作稳定性和数据重复性,无论是比值法还是稳光法,两个光敏二极管的温度特性应一致。同时介绍了一种测量光敏二极管(PIN)温度特性的简易方法     

Optical neural chips

An array of photodetectors, each having a variable sensitivity, forms the most important component of our two gallium arsenide chips. We designed the optical neurochip so that variable sensitivity photodiodes are monolithically integrated on top of an LED array, serving both as fast analog multipliers and as on-chip weight storage elements with learning capability. Our artificial retina device combines a VSPD array with a neural network for postprocessing, allowing us to perform fast, yet flexible, processing operations on projected images