Despite rapid advancements in lidar technology,extremely long-range observation remains a signifi⁃cant challenge.Recently,2μm lasers have demonstrated a potential to be applied in CDWL(Coherent Doppler Wind Lidar)sys...Despite rapid advancements in lidar technology,extremely long-range observation remains a signifi⁃cant challenge.Recently,2μm lasers have demonstrated a potential to be applied in CDWL(Coherent Doppler Wind Lidar)system,for its high atmospheric penetration capability through the atmosphere and high potential la⁃ser power.In this study,we present a 2μm balanced detector that consists of a pair of commercial positive-intrin⁃sic-negative(PIN)diodes with a low-noise transimpedance circuit.To meet the high bandwidth requirements,the highspeed transimpedance circuit and bias voltage tuning method were utilized to overcome the large capaci⁃tance of PIN diodes.The circuit transfer function,stability analysis and noise calculation have been studied.The detector was co-packaged with a data acquisition module for convenient data transmission and bias voltage con⁃trol.The characteristics of the detector,including bandwidth,noise and bias voltage influence,are evaluated in laboratory.Results show that the RMS value of the balanced detector background noise is 539μV and the band⁃widths of the two diodes are 110.8 MHz and 110.3 MHz,respectively.The evaluation results show that the bal⁃anced detector meets the wind measurement requirements and allows for a 1.45×increase in bandwidth through bi⁃as voltage tuning.Our work offers insights into lidar detector design and bandwidth enhancement,providing a valuable reference for researchers and professionals in the field.More importantly,it lays a critical foundation for fu⁃ture ultra-long-range and space-borne 2μm coherent wind lidar systems by addressing key device-level challenges.展开更多
In conventional polarization sensitive optical coherence tomography(PS-OCT),phase retar-dation is obtained by the amplitude of P and S polarization only,and the fast axis angle is obtained by the phase difference in P...In conventional polarization sensitive optical coherence tomography(PS-OCT),phase retar-dation is obtained by the amplitude of P and S polarization only,and the fast axis angle is obtained by the phase difference in P and S polarizations via Hilbert transformation.In this paper,we proposed a modifed PS OCT setup in which the phase retardation and fast axis angle are simply expressed as the function of the amplitude ofP and S polarization and their differential signal.Due to the common-path feature between the two channels ofP and S polarization,the fuctuation in the measurement of phase retardation and fast axis angle caused by excess noise and phase noise from the laser source can be reduced by the differential signal of P and S polarization via a modified balance detector.Thus,the signal of phase retardation and fast angle axis in the deep layer of a porcine sample can be improved.展开更多
基金Supported by the National key R&D Program of China(2022YFB3903103,2023YFC3081100)。
文摘Despite rapid advancements in lidar technology,extremely long-range observation remains a signifi⁃cant challenge.Recently,2μm lasers have demonstrated a potential to be applied in CDWL(Coherent Doppler Wind Lidar)system,for its high atmospheric penetration capability through the atmosphere and high potential la⁃ser power.In this study,we present a 2μm balanced detector that consists of a pair of commercial positive-intrin⁃sic-negative(PIN)diodes with a low-noise transimpedance circuit.To meet the high bandwidth requirements,the highspeed transimpedance circuit and bias voltage tuning method were utilized to overcome the large capaci⁃tance of PIN diodes.The circuit transfer function,stability analysis and noise calculation have been studied.The detector was co-packaged with a data acquisition module for convenient data transmission and bias voltage con⁃trol.The characteristics of the detector,including bandwidth,noise and bias voltage influence,are evaluated in laboratory.Results show that the RMS value of the balanced detector background noise is 539μV and the band⁃widths of the two diodes are 110.8 MHz and 110.3 MHz,respectively.The evaluation results show that the bal⁃anced detector meets the wind measurement requirements and allows for a 1.45×increase in bandwidth through bi⁃as voltage tuning.Our work offers insights into lidar detector design and bandwidth enhancement,providing a valuable reference for researchers and professionals in the field.More importantly,it lays a critical foundation for fu⁃ture ultra-long-range and space-borne 2μm coherent wind lidar systems by addressing key device-level challenges.
基金supported by National Science Council of Taiwan through Grant#NSC95-2221-E-010-015-MY3.
文摘In conventional polarization sensitive optical coherence tomography(PS-OCT),phase retar-dation is obtained by the amplitude of P and S polarization only,and the fast axis angle is obtained by the phase difference in P and S polarizations via Hilbert transformation.In this paper,we proposed a modifed PS OCT setup in which the phase retardation and fast axis angle are simply expressed as the function of the amplitude ofP and S polarization and their differential signal.Due to the common-path feature between the two channels ofP and S polarization,the fuctuation in the measurement of phase retardation and fast axis angle caused by excess noise and phase noise from the laser source can be reduced by the differential signal of P and S polarization via a modified balance detector.Thus,the signal of phase retardation and fast angle axis in the deep layer of a porcine sample can be improved.
