Germanium(Ge)-silicon(Si)-based avalanche photodetectors(APDs)featured by a high absorption coefficient in the near-infrared band have gained wide applications in laser ranging,free space communication,quantum communi...Germanium(Ge)-silicon(Si)-based avalanche photodetectors(APDs)featured by a high absorption coefficient in the near-infrared band have gained wide applications in laser ranging,free space communication,quantum communication,and so on.However,the Ge APDs fabricated by the complementary metal oxide semiconductor(CMOS)process suffer from a large dark current and limited responsivity,imposing a critical challenge on integrated silicon photonic links.In this work,we propose a p-i-n-i-n type Ge APD consisting of an intrinsic germanium layer functioning as both avalanche and absorption regions and an intrinsic silicon layer for dark current reduction.Consequently,a Ge APD with a low dark current,low bias voltage,and high responsivity can be obtained via a standard silicon photonics platform.In the experimental measurement,the Ge APD is characterized by a high primary responsivity of 1.1 A/W with a low dark current as low as 7.42 nA and a dark current density of 6.1×10^(−11) A∕μm^(2) at a bias voltage of−2 V.In addition,the avalanche voltage of the Ge APD is−8.4 V and the measured 3 dB bandwidth of the Ge APD can reach 25 GHz.We have also demonstrated the capability of data reception on 32 Gbps non-return-to-zero(NRZ)optical signal,which has potential application for silicon photonic data links.展开更多
Light detection and ranging(LiDAR)serves as one of the key components in the fields of autonomous driving,surveying mapping,and environment detection.Conventionally,dense points clouds are pursued by LiDAR systems to ...Light detection and ranging(LiDAR)serves as one of the key components in the fields of autonomous driving,surveying mapping,and environment detection.Conventionally,dense points clouds are pursued by LiDAR systems to provide high-definition 3D images.However,the LiDAR is typically used to produce abundant yet redundant data for scanning the homogeneous background of scenes,resulting in power waste and excessive processing time.Hence,it is highly desirable for a LiDAR system to“gaze”at the target of interest by dense scanning and rough sparse scans on the uninteresting areas.Here,we propose a LiDAR structure based on an optical phased array(OPA)with reconfigurable apertures to achieve such a gaze scanning function.By virtue of the cascaded optical switch integrated on the OPA chip,a 64-,128-,192-,or 256-channel antenna can be selected discretionarily to construct an aperture with variable size.The corresponding divergence angles for the far-field beam are 0.32°,0.15°,0.10°,and 0.08°,respectively.The reconfigurable-aperture OPA enables the LiDAR system to perform rough scans via the large beam spots prior to fine scans of the target by using the tiny beam spots.In this way,the OPA-based LiDAR can perform the“gaze”function and achieve full-range scanning efficiently.The scanning time and power consumption can be reduced by 1/4 while precise details of the target are maintained.Finally,we embed the OPA into a frequency-modulated continuous-wave(FMCW)system to demonstrate the“gaze”function in beam scanning.Experiment results show that the number of precise scanning points can be reduced by 2/3 yet can obtain the reasonable outline of the target.The reconfigurable-aperture OPA(RA-OPA)can be a promising candidate for the applications of rapid recognition,like car navigation and robot vision.展开更多
基金National Key Research and Development Program of China(2022YFB2804504)National Natural Science Foundation of China(62090054,61934003,62105173,62105174)+2 种基金Major Scientific and Technological Program of Jilin Province(20210301014GX)Jilin Province Development and Reform Commission(2020C056)Program for Jilin University Science and Technology Innovative Research Team(JLUSTIRT,2021TD-39).
文摘Germanium(Ge)-silicon(Si)-based avalanche photodetectors(APDs)featured by a high absorption coefficient in the near-infrared band have gained wide applications in laser ranging,free space communication,quantum communication,and so on.However,the Ge APDs fabricated by the complementary metal oxide semiconductor(CMOS)process suffer from a large dark current and limited responsivity,imposing a critical challenge on integrated silicon photonic links.In this work,we propose a p-i-n-i-n type Ge APD consisting of an intrinsic germanium layer functioning as both avalanche and absorption regions and an intrinsic silicon layer for dark current reduction.Consequently,a Ge APD with a low dark current,low bias voltage,and high responsivity can be obtained via a standard silicon photonics platform.In the experimental measurement,the Ge APD is characterized by a high primary responsivity of 1.1 A/W with a low dark current as low as 7.42 nA and a dark current density of 6.1×10^(−11) A∕μm^(2) at a bias voltage of−2 V.In addition,the avalanche voltage of the Ge APD is−8.4 V and the measured 3 dB bandwidth of the Ge APD can reach 25 GHz.We have also demonstrated the capability of data reception on 32 Gbps non-return-to-zero(NRZ)optical signal,which has potential application for silicon photonic data links.
基金Program for Jilin University Science and Technology Innovative Research Team(2021TD-39)Jilin Provincial Development and Reform Commission Project(2020C056)+2 种基金Major Scientific and Technological Program of Jilin Province(20210301014GX)National Natural Science Foundation of China(62105173,62105174,61934003,62090054)National Key Research and Development Program of China(2022YFB2804504)。
文摘Light detection and ranging(LiDAR)serves as one of the key components in the fields of autonomous driving,surveying mapping,and environment detection.Conventionally,dense points clouds are pursued by LiDAR systems to provide high-definition 3D images.However,the LiDAR is typically used to produce abundant yet redundant data for scanning the homogeneous background of scenes,resulting in power waste and excessive processing time.Hence,it is highly desirable for a LiDAR system to“gaze”at the target of interest by dense scanning and rough sparse scans on the uninteresting areas.Here,we propose a LiDAR structure based on an optical phased array(OPA)with reconfigurable apertures to achieve such a gaze scanning function.By virtue of the cascaded optical switch integrated on the OPA chip,a 64-,128-,192-,or 256-channel antenna can be selected discretionarily to construct an aperture with variable size.The corresponding divergence angles for the far-field beam are 0.32°,0.15°,0.10°,and 0.08°,respectively.The reconfigurable-aperture OPA enables the LiDAR system to perform rough scans via the large beam spots prior to fine scans of the target by using the tiny beam spots.In this way,the OPA-based LiDAR can perform the“gaze”function and achieve full-range scanning efficiently.The scanning time and power consumption can be reduced by 1/4 while precise details of the target are maintained.Finally,we embed the OPA into a frequency-modulated continuous-wave(FMCW)system to demonstrate the“gaze”function in beam scanning.Experiment results show that the number of precise scanning points can be reduced by 2/3 yet can obtain the reasonable outline of the target.The reconfigurable-aperture OPA(RA-OPA)can be a promising candidate for the applications of rapid recognition,like car navigation and robot vision.
