Terahertz Direct Detectors Based on Superconducting Hot Electron Bolometers with Microwave Biasing

Terahertz （THz） direct detectors based on superconducting niobium nitride （NbN） hot electron bolometers （HEBs） with microwave （MW） biasing are studied. The MW is used to bias the HEB to the optimum point and to readout the impedance changes caused by the incident THz signals. Compared with the thermal biasing method, this method would be more promising in large scale array with simple readout. The used NbN HEB has an excellent performance as heterodyne detector with the double sideband noise temperature （T N） of 403K working at 4.2K and 0.65THz. As a result, the noise equivalent power of 1.5pW/Hz 1/2 and the response time of 64ps are obtained for the direct detectors based on the NbN HEBs and working at 4.2K and 0.65THz.

Progress of the bolometer diagnostic system on EAST

Measurements of the total radiated power and its spatial distribution are crucial for fusion research.On the experimental advanced superconducting tokamak(EAST),both the metal foil resistive bolometer and the absolute extreme ultraviolet(AXUV)photodiodes have been used to quantify the radiated power.This article introduces the latest improvement of the bolometer diagnostic system on EAST.It also details the successful design and installation of new divertor AXUV cameras,which are dedicated to the investigation of divertor physics.The shielding components of the bolometer detector have been refined,and the article provides a detailed exposition of the double shielding structures that have been verified as effective in microwave shielding.Additionally,the changes in the radiated power distribution in the divertor region during the plasma detachment process are measured using the divertor AXUV camera.Finally,the radiated power measured by the AXUV detector and metal foil resistive bolometer are compared,and different detector performances are presented.

高温超导Bolometer的原理性实验

简要介绍了用固态反应法制备出高温超导体材料。材料经切磨减薄并压焊引线后制成超导测辐射热计(Bolometer)实验芯片,芯片安装在带窗口的低温恒温器中,在材料中点转变温度128K附近观测到了明显的辐照热敏效应,直流灵敏度约1V/W。

超导薄膜制 Bolometer 器件的微透镜红外增强

采用离子束刻蚀制备线列熔凝石英柱微透镜阵列，准分子激光扫描消融法淀积性能均匀且稳定性良好的ＹＢａ２Ｃｕ３Ｏ７－δ高温超导薄膜，湿法刻蚀制备超导薄膜器件，微透镜阵列与超导薄膜器件用胶粘合构成组合红外探测器，测试了组合器件在１～５ｍ红外波段的光响应特性．

非制冷红外探测器研究进展(特邀)

非制冷红外探测器由于无需制冷装置,能够工作在室温状态下,具有成本低、体积小、功耗低等特点,在红外领域得到了广泛的应用。在军事应用方面,非制冷型探测器的应用逐渐进入了之前制冷型探测器的应用范围,大量应用在一些低成本的武器系统,甚至在一些应用领域取代了原来的非制冷型探测器。在民用领域方面,更表现出了其价格和使用方便的优势,在民用车载夜视、安防监控等应用领域引起了广泛的兴趣和关注。文中介绍了Bolometer、热释电、热电堆等几种典型非制冷红外探测器的工作原理,列举了目前已实现商业化应用的主要产品在国内外的情况,着重介绍了目前应用最广泛的Bolometer器件主流产品的像元间距、阵列规格、性能及其封装发展的情况。除了已实现商业化应用的Bolometer、热释电、SOI二极管等探测器等产品,还详细介绍了一些非制冷探测新技术或新型器件:比如超表面在增强某些波段吸收方面的应用,新材料的Bolometer探测器、双材料新型非制冷器件、石墨烯、量子点、纳米线等光电探测技术的研究进展。最后文章还对今后非制冷红外探测器的发展趋势作了预测。

高温超导Bolometer研制

Bolometer是一种宽带红外信号检测器,它被广泛用于检测低速远红外信号源.它的应用背景是器件吸收热辐射将产生温度变化,致使器件的电阻发生灵敏变化,从而达到检测信号的目的.理论计算表明,Bolometer的电压响应率R_v,可以由下式表示:

TlBaCaCuO High Temperature Superconducting Bolometer

Meanders of thin films of TlBa 2Ca 2CuO 2 have been used to make radiation bolometers. Using cw HeNe at 632 nm the peak responsivity of these films is measured to be 0.560 V/W at the temperature of 106.0 K. The present experimental data agree well with bolometric response of irradiated films, and the calculations are presented to support this conclusion.

INFRARED DETECTOR USING SUPERCONDUCTING YBa_2Cu_3O_7-δTHIN FILMS

The patterning technologies and process order of high Tc(86K) super-conducting film bolometers have been studied. After the deposition, a conventional lithographic process was used to pattern the films with aqueous solution of HCl, and then the films were transferred into a tube furnace for annealing to form superconducting film. It eliminates the degradation of patterning process. The bolometric responsivity of approximately 34. 32 V/W is measured, and the detectivity is greater than 1. 62× 108cm · Hz1/2 · W-1, the noise equivalent powers NEP is 2. 1×10-9W.

Infrared Imaging Bolometer for the HL-2A Tokamak

An infrared imaging bolometer diagnostic has been upgraded recently to be adapted for the complications of the signal-to-noise ratio arising from the low level of plasma radiation and high reflectivity of low energy photon（〈6.2 eV）.It utilizes a platinum foil,blackened on both sides with graphite spray,as the bolometer detector.The advantage of the blackened foil is the light absorption extending into the infrared.After a careful calibration of the foil,the incident power density distribution on the foil is determined by solving the heat diffusion equation with a numerical technique.The local plasma radiated power density is reconstructed with a minimum fisher information regularization method by assuming plasma emission toroidal symmetry.Comparisons of the results and the profiles measured by an ordinary bolometric detector demonstrate that this method is good enough to provide the plasma radiated power pattern.The typical plasma radiated power density distribution before and after high mode（H-mode） transition is firstly reconstructed with the infrared imaging bolometer.Moreover,during supersonic molecular beam injection（SMBI）,an enhanced radiation region is observed at the edge of the plasma.

Noise temperature distribution of superconducting hot electron bolometer mixers

We report on the investigation of optimal bias region of a wide-band superconducting hot electron bolometer(HEB)mixer in terms of noise temperature performance for multi-pixel heterodyne receiver application in the 5-meter Dome A Terahertz Explorer(DATE5)telescope.By evaluating the double sideband(DSB)receiver noise temperature(Trec)across a wide frequency range from 0.2 THz to 1.34 THz and with a large number of bias points,a broad optimal bias region has been observed,illustrating a good bias applicability for multipixel application since the performance of the HEB mixer is uniquely determined by each bias point.The noise temperature of the HEB mixer has been analyzed by calibrating the noise contribution of all RF components,whose transmissions have been measured by a time-domain spectroscopy.The corrected noise temperature distribution shows a frequency independence relation.The dependence of the optimal bias region on the bath temperature of the HEB mixer has also been investigated,the bath temperature has limited effect on the lowest receiver noise temperature until 7 K,however the optimal bias region deteriorates obviously with increasing bath temperature.

On the MOSFET-Based Temperature Sensitive Element for Bolometer Application

This paper focuses on the study of thermal performances of MOS （metal-oxide-semiconductor） transistors for uncooled infrared bolometer applications. Such devices can be used in various applications both military and civil, such as defence and security, medical applications, industrial surveillance, etc. Series of measurements were conducted to obtain TCC （temperature coefficient of current） versus gate voltage and temperature curves. The TCC is a figure of merit for a device used as the sensitive element in a bolometer that represents its sensitivity to temperature and as such is a good indicator of the detector attainable performance. The measurements were confronted to Atlas simulations, and showed that in the subthreshold region the TCC ranges from 4%/K all the way to 9%/K which represents a great improvement compared to state of the art thermistor bolometers. Analytic expressions of the TCC are also derived from current equations of the MOSFET （MOS field effect transistor） drain current to help understanding the effect of drain to source voltage, mobility, temperature and threshold voltage sensibility to temperature, in all three operation modes of the transistor （subthreshold, ohmic and saturation）. It was also determined that gate length does not have an influence on the TCC until short channel effects are factored in.

Experimental study of Fourier transform spectrometer based on MEMS micro-mirror

We propose a new Fourier transform spectrometer based on programmable microelectromechanical systems （MEMS） micro-mirror and an improved Michelson interferometer. The principle of the spectrometer is theoretically analyzed. A signal acquisition unit and an experimental set-up are designed. The spectrum of the polychromatie light source is obtained at a slantwise reflector angle of O.238°. The spectrum is analyzed by this system within the near infrared. The experimental results show that the spectral accuracy is less than 3 nm, and the signal-to-noise ratio （SNR） is 18 dB. The spectral resolution is less than 16 nm.

YBCO半导体薄膜及Bolometer特性

就Si为衬底的钇钡铜氧 (分子式 :Y1Ba2 Cu3 O7-δ,δ≥ 0 5 ,简称YBCO)薄膜的半导体性质 ,及用于红外测辐射热计 (Bolometer)的探测性能进行了研究 .通过测定温度电阻系数 (TCR)和霍尔 (Hall)系数 ,并采用XRD、拉曼散射光谱等手段分析了YBCO半导体薄膜的微观结构和光谱响应特性 ,认为该薄膜是非制冷红外焦平面的新型探测元材料 .

Study of CdMoO4 crystal for a neutrinoless double beta decay experiment with ^116Cd and ^100Mo nuclides

The scintillation properties of a CdMoO4 crystal have been investigated experimentally.The fluorescence yields and decay times measured from 22 K to 300 K demonstrate that CdMoO4 crystal is a good candidate for an absorber for a bolometer readout,for both heat and scintillation signals.The results from Monte Carlo studies,taking the backgrounds from 2ν2β of^100 42Mo ^116 48Cd） and internal trace nuclides ^214Bi and ^208Tl into account,show that the expected sensitivity of a CdMoO4 bolometer for neutrinoless double beta decay experiments with an exposure of 100kg·years is one order of magnitude higher than those of the current sets of the limT1/2^0νββ of ^100 42Mo and ^116 48Cd.

Superconducting hot-electron bolometer mixers and their applications

Superconducting hot electron bolometer(HEB)mixers are the most sensitive heterodyne detectors at frequencies beyond 1 THz,and are used for many astronomical observations.HEB,consisting of a narrow and short superconducting thin film patch connected to an antenna via contact pads,is brought into a highly sensitive operating regime by applying a DC current and a certain amount of local-oscillator power.Potentially,superconducting HEB mixers are capable of exhibiting high sensitivity for frequencies up to several tens of THz,as their output noise and conversion gain are nearly frequency independent according to the mixing mechanism.Moreover,the understanding of mixing mechanism has evolved over time from lumped-element model to distributed hot-spot model.In this review,we provide an overview of theoretical and experimental studies on HEBs and their applications,especially in astronomical observations on ground,airborne and space telescopes.

Possibilities of the practical use of a stationary strain gradient in the interelectrode volume of unpolarized ferroceramic plates

It has been established that in plates made of hot-pressed ferroelectric ceramics PZT-19(Tc=300℃),after metal electrodes from Ag are burned into opposite surfaces with different depths of mechanical damage,counter-directional stationary deformation gradients and,accordingly,internal electric displacement fields create a stationary flexoelectric effect.As a result,unpolarized ceramics below the Curie temperature become a pyroelectric,and above it become a pyroelectric bolometer.After polishing the less damaged surface and replacing the Ag(valency v=3)electrode with Cr(v=6)by thermal evaporation in vacuum from the intact surface,a new thermally stable polarization is created,directed from the damaged surface in the interelectrode volume.Such plates have an asymmetric dielectric hysteresis loop,retain the values of the pyroelectric effect and piezoelectric effect in the ferroelectric phase,as well as the bolometric effect in the paraelectric phase after repeated heating cycles to 400℃ and cooling to T_(norm).