HIRFL-CSR外靶终端上硅微条探测器阵列的搭建

硅微条探测器因具有很强的位置分辨率与能量分辨率而在世界各大核物理实验室得到广泛应用。中国科学院近代物理研究所研制了性能优越、位置精度达到0.5 mm×0.5 mm的双面硅微条探测器,用于HIRFL-CSR的外靶实验终端谱仪(ETF)上,用作径迹测量以及△E-E望远镜系统△E的探测。硅微条探测器体积小、集成度高,利用柔性印刷电路板(FPCB)引出信号,配合ASIC芯片的前端电路,能够方便地给出每一条的能量信息和位置信息。在此详细阐述了在HIRFL-CSR的ETF上双面硅微条探测器阵列的搭建,并测量了放射源在真空中探测单元的能量分辨本领。结果表明,该硅条探测器的每个探测单元对5~9 MeV能量的α粒子的能量分辨率在1%左右。     

High speed pseudorandom modulation fiber laser ranging system

A laser ranging system using all fiber high speed pseudorandom （PN） coded laser at 1550 nm and photon counting is proposed to realize high spatial resolution. Different lengths of PN code are employed in the optical fiber delay ranging test, the results show the improvement in both ranging accuracy and signal-tonoise ratio （SNR） as PN code trains increase. A ranging accuracy of 3 cm is acquired when transmitting pulses propagate to a target of 1.77 km away and received by an InGaAs/InP avalanche photodiode （APD）. Simulation is also carried out under space borne condition based on current system. The system is demonstrated to have a potential for remote ranging and imaging.     

GaN-based p–i–n ultraviolet photodetectors with a thin p-type GaN layer on patterned sapphire substrates

We study the performance of GaN-based p–i–n ultraviolet(UV) photodetectors(PDs) with a 60 nm thin ptype contact layer grown on patterned sapphire substrate(PSS). The PDs on PSS exhibit a low dark current of ~2 pA under a bias of-5 V, a large UV/visible rejection ratio of ~7×103, and a high-quantum efficiency of ~40% at 365 nm under zero bias. The average quantum efficiency of the PDs still remains above 20% in the deep-UV region from 280 to 360 nm. In addition, the noise characteristics of the PDs are also discussed, and the corresponding specific detectivities limited by the thermal noise and the low-frequency 1/f noise are calculated.     

用于红外探测器的高红外吸收率结构研究进展

高红外吸收是实现高灵敏度红外探测器的一个重要途径。探测器的响应率与热吸收率紧密相关。高红外吸收将提升红外探测器的探测性能。鉴于高吸收率的重要性,对国内外研究中典型的高红外吸收结构的研究进展进行介绍。目前典型新型高吸收结构有基于新型材料(如超材料)的高吸收结构和基于金属光栅高吸收结构。研究表明这些结构在某些波段可实现近100%的完美吸收,是发展高灵敏探测器的新途径。     

化学发光法大气氮氧化物浓度自动分析仪中光信号探测模块温控系统设计

化学发光法是测量低浓度的大气氮氧化物含量的有效方法,可用于24h连续自动分析的大气环境监测系统。然而该方法需要高温转换室、高压臭氧发生模块、高温反应室等模块,使得仪器内的环境分布极为复杂,仪器在长时间运行后容易出现灵敏度下降、信噪比降低等现象。针对上述现象,设计了用于仪器的光信号探测模块的温度控制系统。该温控系统基于PID控制原理,通过AVR单片机ATMEGAl6对半导体制冷片（Ther—mo—ElectricCooling,TEC）的闭环控制来实现温度的精密控制。实验结果表明,该系统可以使光信号探测模块的温度控制在5℃±0．1℃,光电倍增管的暗噪声从25℃时的363个／s下降到5℃时的8个／s光子数,噪声波动标准差也从22降到3,能够很好地满足系统对信号探测稳定性的要求。     

2014全国光电技术与光机电系统学术会议(征文通知)

正中国光学学会光电技术专业委员会和中国仪器仪表学会光机电技术与系统集成分会将于2014年10月下旬在南京联合主办"2014全国光电技术与光机电系统学术会议"。热诚欢迎从事光电技术、光学工程、激光与光电子学和光机电仪器等领域的科学研究人员和工程技术人员参加会议并积极投稿,大会将为每位作者提供学术交流的机会。会议还将邀请工作在科研第一线的院士和知名学者参加会议,并为大家做邀请报告。同时也热忱欢迎从事光电产品研发、生产和销售的公司、厂家参与产品展示,届时主办单位将提供产     

基于改进CKF的光电跟踪伺服系统二阶滑模控制

传统的光电跟踪伺服系统滑模控制中,对目标位移信号微分以求取速度、加速度等运动状态的方法会影响控制的精度和稳定性。针对这一缺点,提出了基于改进容积卡尔曼滤波(CKF)的二阶滑模控制算法。基于系统原理,建立了系统模型;应用限定下界法改进了CKF算法以提高目标状态估计的准确度;应用超螺旋算法设计了二阶滑模控制器,并将滤波预测的目标状态作为系统输入进行仿真实验。结果表明,相对于传统的二阶滑模控制,所设计的控制方法提高了控制精度,减小了抖振,且具有更好的稳定性。     

Sixteen-element Ge-on-SOI PIN photo-detector arrays for parallel optical interconnects

We describe the structure and testing of one-dimensional array parallel-optics photo-detectors with 16 photodiodes of which each diode operates up to 8 Gb/s. The single element is vertical and top illuminated 30μm-diameter silicon on insulator （Ge-on-SOI） PIN photodetector. High-quality Ge absorption layer is epitaxially grown on SO1 substrate by the ultra-high vacuum chemical vapor deposition （UHV-CVD）. The photodiode exhibits a good responsivity of 0.20 A/W at a wavelength of 1550 nm. The dark current is as low as 0.36/aA at a reverse bias of 1 V, and the corresponding current density is about 51 mA/cm2. The detector with a diameter of 30 t.trn is measured at an incident light of 1.55 μm and 0.5 mW, and the 3-dB bandwidth is 7.39 GHz without bias and 13.9 GHz at a reverse bias of 3 V. The 16 devices show a good consistency.     

Online charge calibration of LHAASO-WCDA——a study with the engineering array

LHAASO-WCDA is a large ground-based water Cherenkov detector array planned to be built at ShangriLa, Yunnan Province, China. As a major component of the LHAASO project, the main purpose of LHAASO-WCDA is to survey the northern sky for very-high-energy（above 100 GeV） gamma ray sources and measure the spectrum. To gain full knowledge of the water Cherenkov technique and to investigate the engineering issues, a 9-cell detector array has been built at the Yang-Ba-Jing site, neighboring the ARGO-YBJ experiment. With the array, charge calibration methods for both low and high ranges of the PMT readout are studied, whose result shows that a precision at several percentages can be reached, which can satisfy the requirement of the detector array. During the long term operation, the charge calibration stability and environmental afection are studied; in this paper, the results are discussed. These calibration methods are proposed to be applied in the future LHAASO-WCDA project.     

A prototype silicon detector system for space cosmic-ray charge measurement

A readout electronics system used for space cosmic-ray charge measurement for multi-channel silicon detectors is introduced in this paper, including performance measurements. A 64-channel charge sensitive ASIC （VA140） from the IDEAS company is used. With its features of low power consumption, low noise, large dynamic range, and high integration, it can be used in future particle detecting experiments based on silicon detectors.