In this study,we developed a single-beam optical trap-based surface-enhanced Raman scattering(SERS)optofluidic molecular fingerprint spectroscopy detection system.This system utilizes a single-beam optical trap to con...In this study,we developed a single-beam optical trap-based surface-enhanced Raman scattering(SERS)optofluidic molecular fingerprint spectroscopy detection system.This system utilizes a single-beam optical trap to concentrate free silver nanoparticles(AgNPs)within an optofluidic chip,significantly enhancing SERS performance.We investigated the optical field distribution characteristics within the tapered fiber using COMSOL simulation software and established a MATLAB simulation model to validate the single-beam optical trap's effectiveness in capturing AgNPs,demonstrating the theoretical feasibility of our approach.To verify the particle capture efficacy of the system,we experimentally controlled the optical trap's on-off state to manage the capture and release of particles precisely.The experimental results indicated that the Raman signal intensity in the capture state was significantly higher than in the non-capture state,confirming that the single-beam optical trap effectively enhances the SERS detection capability of the optofluidic detection system.Furthermore,we employed Raman mapping techniques to investigate the impact of the capture area on the SERS effect,revealing that the spectral intensity of molecular fingerprints in the laser-trapping region is significantly improved.We successfully detected the Raman spectrum of crystal violet at a concentration of 10^(−9)mol/L and pesticide thiram at a concentration of 10^(−5)mol/L,further demonstrating the ability of the single-beam optical trap in enhancing the molecular fingerprint spectrum identification capability of the SERS optofluidic chips.The optical trapping SERS optofluidic detection system developed in this study,as a key component of an integrated optoelectronic sensing system,holds the potential for integration with portable high-power lasers and high-performance Raman spectrometers.This integration is expected to advance highly integrated technologies and significantly enhance the overall performance and portability of optoelectronic sensing systems.展开更多
Frequency-swept interferometry(FSI) is a well-known ranging technique, but it suffers from three problems, namely, the Doppler effect, the frequency-sweep nonlinearity, as well as the slow frequency-sweep rate. The fi...Frequency-swept interferometry(FSI) is a well-known ranging technique, but it suffers from three problems, namely, the Doppler effect, the frequency-sweep nonlinearity, as well as the slow frequency-sweep rate. The first two problems hinder the measurement accuracy, while the third problem limits the measurement rate. In this paper, we present a dynamic FSI(DFSI) that solves these three fundamental problems simultaneously. The DFSI consists of two auxiliary interferometers(AU1 and AU2) and two measurement interferometers(FSI and frequency-fixed interferometry(FFI)). We use FSI to obtain the Doppler and nonlinearity affected ranging signal, AU1 to monitor the frequency-tuning nonlinearity in the frequency-swept laser(FSL), and FFI and AU2 to constitute a laser vibrometer for monitoring the target motion-induced Doppler effect. Then, a novel signal fusion processing technique is applied to reconstruct the real dynamic distance from the above-measured signals. The dynamic ranging error caused by the Doppler effect and frequency-sweep nonlinearity in FSI can be eliminated and the dynamic distance at each sampling point can be obtained. The validity of this method is demonstrated by numerical experiments.展开更多
We report the numerical and experimental studies of the two-dimensional Brillouin gain spectrum(BGS)distribution deformation induced by the self-phase modulation in the Brillouin optical time domain reflectometry(BOTD...We report the numerical and experimental studies of the two-dimensional Brillouin gain spectrum(BGS)distribution deformation induced by the self-phase modulation in the Brillouin optical time domain reflectometry(BOTDR)with a 20.6 km sensing distance.The BGS distribution deformation is investigated by analyzing the evolution of the point spread function along the fiber in the two-dimensional model of the BOTDR.In the simulation and experimental results,the specific deformation degree of the BGS distribution induced by the self-phase modulation is related to the pump pulse profile,pump pulse peak power,BGS demodulation method,and detected scattered light component.By comprehensively analyzing the evolution of the point spread function induced by the self-phase modulation and using the image deconvolution,a typical BOTDR sensor with a 25 ns pump pulse reaches the 20 cm spatial resolution over the 20.6 km sensing fiber.展开更多
In this study,we present a dual-Fizeau-interferometer-based high-speed and wide-range fiber-optic Fabry-Perot(F-P)demodulation system.We employ two Fizeau interferometers with air cavity thickness satisfying the quadr...In this study,we present a dual-Fizeau-interferometer-based high-speed and wide-range fiber-optic Fabry-Perot(F-P)demodulation system.We employ two Fizeau interferometers with air cavity thickness satisfying the quadrature requirement to increase the demodulation speed and broaden the demodulation range in order to address the issues of the existing fiber F-P demodulation system's sluggish demodulation rate and limited range.In order to investigate the demodulation properties of the dual-Fizeau-interferometer-based demodulation system,we derive and create a theoretical model of the system.The theoretical model,which primarily consists of the structural design of the interferometer and the study of the center wavelength of the light sources and their bandwidth selection,is used to construct the optical structure of the demodulation system.According to the calculation results,the demodulated signal exhibits the best contrast ratio when the two light sources'respective center wavelengths are 780nm and 850nm,and their bandwidths are 28nm and 30 nm.Finally,we finish evaluating the demodulation system's demodulation performance,parameter calibration,and assembly debugging.The test results demonstrate the constant operation of the demodulation system,an update rate of 100kHz,a demodulation range of 4.74μm,and a cavity length resolution of approximately 5 nm.Additionally,the system can perform high speed demodulation thanks to the light emitting diode's(LED's)nanosecond level switching speed and the usage of a single point detector.展开更多
In this paper,a fiber grating demodulation system based on two transmission volume Bragg gratings(VBGs)was proposed.In order to resolve the problem that the spectral resolution of the present fiber grating demodulatio...In this paper,a fiber grating demodulation system based on two transmission volume Bragg gratings(VBGs)was proposed.In order to resolve the problem that the spectral resolution of the present fiber grating demodulation system is not high enough,the two transmission VBGs were applied to improve the spectral resolution and reduce the volume of the spectrometer.The diffraction characteristics of the transmission VBGs were analyzed,and the optical path of the two transmission VBGs demodulation system was designed based on the diffraction characteristics.The grating constant,lens parameters,and aberration correction of the system were analyzed and calculated.The calculation showed that the theoretical wavelength range of the demodulation system was from 1525 nm to 1565 nm and the theoretical optical resolution was 60 pm when the grating constant was 0.9168,the angle between two transmission VBGs was 89°,the focal length of the collimator was 60 mm,and the focal length of the imaging lens was 131.5 mm.The aberration of the system was well corrected by using a lens as the collimator and a reflector as the imaging lens.The system principle prototype was assembled and calibrated,and its performances were experimentally investigated.The results showed that the spectrometer worked stably,with a wavelength range from 1525 nm to 1565 nm,an optical wavelength resolution of 65.3 pm,and a high demodulation speed of 10 kHz.展开更多
基金financial supports from National Natural Science Foundation of China(62175023).
文摘In this study,we developed a single-beam optical trap-based surface-enhanced Raman scattering(SERS)optofluidic molecular fingerprint spectroscopy detection system.This system utilizes a single-beam optical trap to concentrate free silver nanoparticles(AgNPs)within an optofluidic chip,significantly enhancing SERS performance.We investigated the optical field distribution characteristics within the tapered fiber using COMSOL simulation software and established a MATLAB simulation model to validate the single-beam optical trap's effectiveness in capturing AgNPs,demonstrating the theoretical feasibility of our approach.To verify the particle capture efficacy of the system,we experimentally controlled the optical trap's on-off state to manage the capture and release of particles precisely.The experimental results indicated that the Raman signal intensity in the capture state was significantly higher than in the non-capture state,confirming that the single-beam optical trap effectively enhances the SERS detection capability of the optofluidic detection system.Furthermore,we employed Raman mapping techniques to investigate the impact of the capture area on the SERS effect,revealing that the spectral intensity of molecular fingerprints in the laser-trapping region is significantly improved.We successfully detected the Raman spectrum of crystal violet at a concentration of 10^(−9)mol/L and pesticide thiram at a concentration of 10^(−5)mol/L,further demonstrating the ability of the single-beam optical trap in enhancing the molecular fingerprint spectrum identification capability of the SERS optofluidic chips.The optical trapping SERS optofluidic detection system developed in this study,as a key component of an integrated optoelectronic sensing system,holds the potential for integration with portable high-power lasers and high-performance Raman spectrometers.This integration is expected to advance highly integrated technologies and significantly enhance the overall performance and portability of optoelectronic sensing systems.
基金supported by the Sustainably Supported Foundation of SASTIND (No.HTKJ2021KL504008)the National Natural Science Foundation of China (No.51805054)+1 种基金the China Postdoctoral Science Foundation (No.2018M643405)the Technology Innovation Platform Project of Aero Engine Corporation of China (No.SHYS-GXDPL-18)。
文摘Frequency-swept interferometry(FSI) is a well-known ranging technique, but it suffers from three problems, namely, the Doppler effect, the frequency-sweep nonlinearity, as well as the slow frequency-sweep rate. The first two problems hinder the measurement accuracy, while the third problem limits the measurement rate. In this paper, we present a dynamic FSI(DFSI) that solves these three fundamental problems simultaneously. The DFSI consists of two auxiliary interferometers(AU1 and AU2) and two measurement interferometers(FSI and frequency-fixed interferometry(FFI)). We use FSI to obtain the Doppler and nonlinearity affected ranging signal, AU1 to monitor the frequency-tuning nonlinearity in the frequency-swept laser(FSL), and FFI and AU2 to constitute a laser vibrometer for monitoring the target motion-induced Doppler effect. Then, a novel signal fusion processing technique is applied to reconstruct the real dynamic distance from the above-measured signals. The dynamic ranging error caused by the Doppler effect and frequency-sweep nonlinearity in FSI can be eliminated and the dynamic distance at each sampling point can be obtained. The validity of this method is demonstrated by numerical experiments.
基金supported by the National Natural Science Foundation of China(Grant Nos.62105045 and 62205037)the National Science Fund for Distinguished Young Scholars(Grant No.61825501)Chongqing Natural Science Foundation of Innovative Research Groups(Grant No.cstc2020jcyj-cxttX0005).
文摘We report the numerical and experimental studies of the two-dimensional Brillouin gain spectrum(BGS)distribution deformation induced by the self-phase modulation in the Brillouin optical time domain reflectometry(BOTDR)with a 20.6 km sensing distance.The BGS distribution deformation is investigated by analyzing the evolution of the point spread function along the fiber in the two-dimensional model of the BOTDR.In the simulation and experimental results,the specific deformation degree of the BGS distribution induced by the self-phase modulation is related to the pump pulse profile,pump pulse peak power,BGS demodulation method,and detected scattered light component.By comprehensively analyzing the evolution of the point spread function induced by the self-phase modulation and using the image deconvolution,a typical BOTDR sensor with a 25 ns pump pulse reaches the 20 cm spatial resolution over the 20.6 km sensing fiber.
文摘In this study,we present a dual-Fizeau-interferometer-based high-speed and wide-range fiber-optic Fabry-Perot(F-P)demodulation system.We employ two Fizeau interferometers with air cavity thickness satisfying the quadrature requirement to increase the demodulation speed and broaden the demodulation range in order to address the issues of the existing fiber F-P demodulation system's sluggish demodulation rate and limited range.In order to investigate the demodulation properties of the dual-Fizeau-interferometer-based demodulation system,we derive and create a theoretical model of the system.The theoretical model,which primarily consists of the structural design of the interferometer and the study of the center wavelength of the light sources and their bandwidth selection,is used to construct the optical structure of the demodulation system.According to the calculation results,the demodulated signal exhibits the best contrast ratio when the two light sources'respective center wavelengths are 780nm and 850nm,and their bandwidths are 28nm and 30 nm.Finally,we finish evaluating the demodulation system's demodulation performance,parameter calibration,and assembly debugging.The test results demonstrate the constant operation of the demodulation system,an update rate of 100kHz,a demodulation range of 4.74μm,and a cavity length resolution of approximately 5 nm.Additionally,the system can perform high speed demodulation thanks to the light emitting diode's(LED's)nanosecond level switching speed and the usage of a single point detector.
基金This work was supported by the National Natural Science Foundation of China(Grant No.51875067)the Fundamental Research Funds of Central Universities(Grant No.2019CDJGFGD003).
文摘In this paper,a fiber grating demodulation system based on two transmission volume Bragg gratings(VBGs)was proposed.In order to resolve the problem that the spectral resolution of the present fiber grating demodulation system is not high enough,the two transmission VBGs were applied to improve the spectral resolution and reduce the volume of the spectrometer.The diffraction characteristics of the transmission VBGs were analyzed,and the optical path of the two transmission VBGs demodulation system was designed based on the diffraction characteristics.The grating constant,lens parameters,and aberration correction of the system were analyzed and calculated.The calculation showed that the theoretical wavelength range of the demodulation system was from 1525 nm to 1565 nm and the theoretical optical resolution was 60 pm when the grating constant was 0.9168,the angle between two transmission VBGs was 89°,the focal length of the collimator was 60 mm,and the focal length of the imaging lens was 131.5 mm.The aberration of the system was well corrected by using a lens as the collimator and a reflector as the imaging lens.The system principle prototype was assembled and calibrated,and its performances were experimentally investigated.The results showed that the spectrometer worked stably,with a wavelength range from 1525 nm to 1565 nm,an optical wavelength resolution of 65.3 pm,and a high demodulation speed of 10 kHz.
