The quest for solar-blind photodetectors with outstanding optoelectronic properties and weak signals detection capability is essential for their applications in the field of imaging,communication,warning,etc.To date,G...The quest for solar-blind photodetectors with outstanding optoelectronic properties and weak signals detection capability is essential for their applications in the field of imaging,communication,warning,etc.To date,Ga_(2)O_(3)has demonstrated potential for high-performance solar-blind photodetectors.However,the performance usually decays superlinearly at low light intensities due to carrier-trapping effect,which limits the weak signal detection capability of Ga_(2)O_(3)photodetectors.Herein,a Ga_(2)O_(3)solarblind photodetector with ultra-thin absorbing medium has been designed to restrain trapping of photo-generated carriers during the transporting process by shortening the carrier transport distance.Meanwhile,multiple-beam interference is employed to enhance the absorption efficiency of the Ga_(2)O_(3)layer using an Al/Al_(2)O_(3)/Ga_(2)O_(3)structure.Based on the ultra-thin absorbing medium with enhanced absorption efficiency,a 7×7 flexible photodetector array is developed,and the detectivity can reach 1.7×10^(15)Jones,which is among the best values ever reported for Ga_(2)O_(3)photodetectors.Notably,the performance of the photodetector decays little as the illumination intensity is as weak as 5 nW/cm2,revealing the capacity to detect ultra-weak signals.In addition,the flexible photodetector array can execute the functions of imaging,spatial distribution of light source intensity,real-time light trajectory detection,etc.Our results may provide a route to high-performance solar-blind photodetectors for ultra-weak light detection.展开更多
We demonstrate a blind zone-suppressed and flash-emitting solid-state Lidar based on lens-assisted beam-steering technology.As a proof-of-concept demonstration,with the design of a subwavelength-gap 1D long-emitter ar...We demonstrate a blind zone-suppressed and flash-emitting solid-state Lidar based on lens-assisted beam-steering technology.As a proof-of-concept demonstration,with the design of a subwavelength-gap 1D long-emitter array and multiwavelength flash beam emitting,the device was measured to have 5%blind zone suppression,0.06°/point-deflection step,and 4.2μs scanning speed.In time-of-flight ranging experiments,Lidar systems have a field of view of 11.3°×8.1°(normal device)or 0.9°×8.1°(blind-zone suppressed device),far-field number of resolved points of 192,and a detection distance of 10 m.This work demonstrates the possibility that a new integrated beam-steering technology can be implemented in a Lidar without sacrificing other performance.展开更多
For researching the residual stress distribution characteristics of the different large thickness titanium alloy joints by electron beam welding,under heat treatment or non-heat treatment conditions,the changes in res...For researching the residual stress distribution characteristics of the different large thickness titanium alloy joints by electron beam welding,under heat treatment or non-heat treatment conditions,the changes in residual stress distribution characteristics of electron beam welding joints,which thickness is 50 mm,were measured using blind-hole method with local layer-by-layer removal.Effect of post-welding heat treatment on the residual stress distribution also studied.The results show that blind-hole method with local layer-by-layer removal is suitable to measure residual stresses in thick plate,and good to reflect the welded residual stress distribution of large gradient.Residual stress of the test samples in the weld and heat affected zone has high stress level,and internal stress dramatic changes with thickness in this areas.After heat treatment,the samples' stress distributions were significantly reduced.The samples' transverse and longitudinal residual stress are basically the same.Homogenization is obvious.展开更多
阵列雷达的主瓣干扰抑制是雷达抗干扰领域的一个难题。提出了一种基于子阵域的盲源分离主瓣抗干扰算法。该算法以特征矩阵近似联合对角化(joint approximate diagonalization of eigen-matrices,JADE)盲源分离算法为基础,与传统的全向...阵列雷达的主瓣干扰抑制是雷达抗干扰领域的一个难题。提出了一种基于子阵域的盲源分离主瓣抗干扰算法。该算法以特征矩阵近似联合对角化(joint approximate diagonalization of eigen-matrices,JADE)盲源分离算法为基础,与传统的全向阵列算法相比,该算法提供了较低的复杂度,尤其是针对大型阵列时,算法的优势更加显著。其设计思路是先将全向阵列划分到子阵域;然后在子阵域的基础上利用多重信号分类和恒虚警检测,设计了一种新的盲源分离信道数预估计方法,为JADE提供先验信息;最后设定盲源分离通道数,使接收信号分离,并将分离信号分别进行脉冲压缩、信号检测等步骤,从而达到雷达主瓣抗干扰的目的。通过仿真分析可知,该方法可以实现目标信号和干扰信号的有效分离,且计算量对比全向阵列有显著降低,具有一定的工程应用前景。展开更多
基金This work was financially supported by the National Key Research and Development Program of China(No.2018YFB0406500)the National Natural Science Foundation of China(Nos.61804136,U1804155,and 62027816)China Postdoctoral Science Foundation(Nos.2018M630829 and 2019T120630).
文摘The quest for solar-blind photodetectors with outstanding optoelectronic properties and weak signals detection capability is essential for their applications in the field of imaging,communication,warning,etc.To date,Ga_(2)O_(3)has demonstrated potential for high-performance solar-blind photodetectors.However,the performance usually decays superlinearly at low light intensities due to carrier-trapping effect,which limits the weak signal detection capability of Ga_(2)O_(3)photodetectors.Herein,a Ga_(2)O_(3)solarblind photodetector with ultra-thin absorbing medium has been designed to restrain trapping of photo-generated carriers during the transporting process by shortening the carrier transport distance.Meanwhile,multiple-beam interference is employed to enhance the absorption efficiency of the Ga_(2)O_(3)layer using an Al/Al_(2)O_(3)/Ga_(2)O_(3)structure.Based on the ultra-thin absorbing medium with enhanced absorption efficiency,a 7×7 flexible photodetector array is developed,and the detectivity can reach 1.7×10^(15)Jones,which is among the best values ever reported for Ga_(2)O_(3)photodetectors.Notably,the performance of the photodetector decays little as the illumination intensity is as weak as 5 nW/cm2,revealing the capacity to detect ultra-weak signals.In addition,the flexible photodetector array can execute the functions of imaging,spatial distribution of light source intensity,real-time light trajectory detection,etc.Our results may provide a route to high-performance solar-blind photodetectors for ultra-weak light detection.
基金National Natural Science Foundation of China(61875122,61922056)。
文摘We demonstrate a blind zone-suppressed and flash-emitting solid-state Lidar based on lens-assisted beam-steering technology.As a proof-of-concept demonstration,with the design of a subwavelength-gap 1D long-emitter array and multiwavelength flash beam emitting,the device was measured to have 5%blind zone suppression,0.06°/point-deflection step,and 4.2μs scanning speed.In time-of-flight ranging experiments,Lidar systems have a field of view of 11.3°×8.1°(normal device)or 0.9°×8.1°(blind-zone suppressed device),far-field number of resolved points of 192,and a detection distance of 10 m.This work demonstrates the possibility that a new integrated beam-steering technology can be implemented in a Lidar without sacrificing other performance.
文摘For researching the residual stress distribution characteristics of the different large thickness titanium alloy joints by electron beam welding,under heat treatment or non-heat treatment conditions,the changes in residual stress distribution characteristics of electron beam welding joints,which thickness is 50 mm,were measured using blind-hole method with local layer-by-layer removal.Effect of post-welding heat treatment on the residual stress distribution also studied.The results show that blind-hole method with local layer-by-layer removal is suitable to measure residual stresses in thick plate,and good to reflect the welded residual stress distribution of large gradient.Residual stress of the test samples in the weld and heat affected zone has high stress level,and internal stress dramatic changes with thickness in this areas.After heat treatment,the samples' stress distributions were significantly reduced.The samples' transverse and longitudinal residual stress are basically the same.Homogenization is obvious.
文摘阵列雷达的主瓣干扰抑制是雷达抗干扰领域的一个难题。提出了一种基于子阵域的盲源分离主瓣抗干扰算法。该算法以特征矩阵近似联合对角化(joint approximate diagonalization of eigen-matrices,JADE)盲源分离算法为基础,与传统的全向阵列算法相比,该算法提供了较低的复杂度,尤其是针对大型阵列时,算法的优势更加显著。其设计思路是先将全向阵列划分到子阵域;然后在子阵域的基础上利用多重信号分类和恒虚警检测,设计了一种新的盲源分离信道数预估计方法,为JADE提供先验信息;最后设定盲源分离通道数,使接收信号分离,并将分离信号分别进行脉冲压缩、信号检测等步骤,从而达到雷达主瓣抗干扰的目的。通过仿真分析可知,该方法可以实现目标信号和干扰信号的有效分离,且计算量对比全向阵列有显著降低,具有一定的工程应用前景。
