This letter explores the distributed multisensor dynamic system, which has uniform sampling velocity and asynchronous sampling data for different sensors, and puts forward a new gradation fusion algorithm of multisens...This letter explores the distributed multisensor dynamic system, which has uniform sampling velocity and asynchronous sampling data for different sensors, and puts forward a new gradation fusion algorithm of multisensor dynamic system. As the total forecasted increment value between the two adjacent moments is the forecasted estimate value of the corresponding state increment in the fusion center, the new algorithm models the state and the forecasted estimate value of every moment. Kalman filter and all measurements arriving sequentially in the fusion period are employed to update the evaluation of target state step by step, on the condition that the system has obtained the target state evaluation that is based on the overall information in the previous fusion period. Accordingly, in the present period, the fusion evaluation of the target state at each sampling point on the basis of the overall information can be obtained. This letter elaborates the form of this new algorithm. Computer simulation demonstrates that this new algorithm owns greater precision in estimating target state than the present asynchronous fusion algorithm calibrated in time does.展开更多
As research on high-sensitivity terahertz sensing and terahertz-matter interactions deepens,the requirements for spectral and spatial resolution in terahertz spectroscopy have become stringent.Existing terahertz time-...As research on high-sensitivity terahertz sensing and terahertz-matter interactions deepens,the requirements for spectral and spatial resolution in terahertz spectroscopy have become stringent.Existing terahertz time-domain spectroscopy(THz-TDS)techniques often struggle to balance these two aspects.Here,we combine asynchronous optical sampling with a photoconductive probe to build a spatial-resolved asynchronous-sampling terahertz spectroscopy(SPRATS)system,which boasts a spatial resolution of20μm and a spectral resolution of 100 MHz.When SPRATS is applied to measure the leaked guided mode resonance(leaked-GMR)in a silicon dual-period grating,this new technique reveals a 6%increase in the quality factor(Q factor)and a 48%improvement in the figure of merit(FoM),compared with traditional 4F THz-TDS.Besides,the SPRATS system's in situ near-field mapping capability with a spatial resolution of 20μm enables direct verification of the leaked-GMR mode.The proposed SPRATS system will undoubtedly propel research endeavors in the realms of highly sensitive terahertz sensing,terahertz nonlinear phenomena,and the R&D of high-Q terahertz devices.展开更多
We report a compact,tunable,self-starting,all-fiber laser-based asynchronous optical sampling(ASOPS)system.Two Er-doped fiber oscillators were used as the pulsed-laser source,whose repetition rate could be set at 100 ...We report a compact,tunable,self-starting,all-fiber laser-based asynchronous optical sampling(ASOPS)system.Two Er-doped fiber oscillators were used as the pulsed-laser source,whose repetition rate could be set at 100 MHz with a tuning range of 1.25 MHz through a fiber delay line.By employing phase-locked and temperature control loops,the repetition rate offset of the two lasers was stabilized with 7.13×10^(−11)fractional instability at an average time of 1 s.Its capabilities in the terahertz regime were demonstrated by terahertz time-domain spectroscopy,achieving a spectral bandwidth of 3 THz with a dynamic range of 30 dB.The large range of repetition rate adjustment in our ASOPS system has the potential to be a powerful tool in the terahertz regime.展开更多
基金Supported by the National Natural Science Foundation of China (No.60434020, 60374020)International Cooperation Item of Henan (No.0446650006)Henan Outstanding Youth Science Fund (No.0312001900).
文摘This letter explores the distributed multisensor dynamic system, which has uniform sampling velocity and asynchronous sampling data for different sensors, and puts forward a new gradation fusion algorithm of multisensor dynamic system. As the total forecasted increment value between the two adjacent moments is the forecasted estimate value of the corresponding state increment in the fusion center, the new algorithm models the state and the forecasted estimate value of every moment. Kalman filter and all measurements arriving sequentially in the fusion period are employed to update the evaluation of target state step by step, on the condition that the system has obtained the target state evaluation that is based on the overall information in the previous fusion period. Accordingly, in the present period, the fusion evaluation of the target state at each sampling point on the basis of the overall information can be obtained. This letter elaborates the form of this new algorithm. Computer simulation demonstrates that this new algorithm owns greater precision in estimating target state than the present asynchronous fusion algorithm calibrated in time does.
基金supported by the National Natural Science Foundation of China(Grant Nos.62027820,61975143,62375203,62205380,62025504,and 61935015)。
文摘As research on high-sensitivity terahertz sensing and terahertz-matter interactions deepens,the requirements for spectral and spatial resolution in terahertz spectroscopy have become stringent.Existing terahertz time-domain spectroscopy(THz-TDS)techniques often struggle to balance these two aspects.Here,we combine asynchronous optical sampling with a photoconductive probe to build a spatial-resolved asynchronous-sampling terahertz spectroscopy(SPRATS)system,which boasts a spatial resolution of20μm and a spectral resolution of 100 MHz.When SPRATS is applied to measure the leaked guided mode resonance(leaked-GMR)in a silicon dual-period grating,this new technique reveals a 6%increase in the quality factor(Q factor)and a 48%improvement in the figure of merit(FoM),compared with traditional 4F THz-TDS.Besides,the SPRATS system's in situ near-field mapping capability with a spatial resolution of 20μm enables direct verification of the leaked-GMR mode.The proposed SPRATS system will undoubtedly propel research endeavors in the realms of highly sensitive terahertz sensing,terahertz nonlinear phenomena,and the R&D of high-Q terahertz devices.
基金This study was supported by the National Natural Science Foundation of China(Nos.12134004,12104162,and 62127804)National Key R&D Program of China(No.2018YFA0306301)+1 种基金Shanghai Municipal Science and Technology Major ProjectChina Postdoctoral Science Foundation(No.2022M711175).
文摘We report a compact,tunable,self-starting,all-fiber laser-based asynchronous optical sampling(ASOPS)system.Two Er-doped fiber oscillators were used as the pulsed-laser source,whose repetition rate could be set at 100 MHz with a tuning range of 1.25 MHz through a fiber delay line.By employing phase-locked and temperature control loops,the repetition rate offset of the two lasers was stabilized with 7.13×10^(−11)fractional instability at an average time of 1 s.Its capabilities in the terahertz regime were demonstrated by terahertz time-domain spectroscopy,achieving a spectral bandwidth of 3 THz with a dynamic range of 30 dB.The large range of repetition rate adjustment in our ASOPS system has the potential to be a powerful tool in the terahertz regime.
