Incoherent optical processing of microwave signals,where low-coherence broadband light sources are employed instead of costly mode locked lasers,has attracted great interest thanks to its wide applications in microwav...Incoherent optical processing of microwave signals,where low-coherence broadband light sources are employed instead of costly mode locked lasers,has attracted great interest thanks to its wide applications in microwave photonics filtering[1–3],arbitrary generation[4–6]and analog to digital conversion[7]。展开更多
A hybrid fiber optical bistable device with electrical feedback has been proposed and analyzed.Bistability operation and some applications for optical signal processing have been realized experimentally .
We propose a novel all-optical sampling method using nonlinear polarization rotation in a semiconductor optical amplifier. A rate-equation model capable of describing the all-optical sampling mechanism is presented in...We propose a novel all-optical sampling method using nonlinear polarization rotation in a semiconductor optical amplifier. A rate-equation model capable of describing the all-optical sampling mechanism is presented in this paper. Based on this model, we investigate the optimized operating parameters of the proposed system by simulating the output intensity of the probe light as functions of the input polarization angle, the phase induced by the polarization controller, and the ori- entation of the polarization beam splitter. The simulated results show that we can obtain a good linear slope and a large linear dynamic range,which is suitable for all-optical sampling. The operating power of the pump light can be less than lmW. The presented all-optical sampling method can potentially operate at a sampling rate up to hundreds GS/s and needs low optical power.展开更多
Multi-wavelength optical information processing systems are commonly utilized in optical neural networks and broadband signal processing.However,their effectiveness is often compromised by frequency-selective response...Multi-wavelength optical information processing systems are commonly utilized in optical neural networks and broadband signal processing.However,their effectiveness is often compromised by frequency-selective responses caused by fabrication,transmission,and environmental factors.To mitigate these issues,this study introduces a deep reinforcement learning calibration(DRC)method inspired by the deep deterministic policy gradient training strategy.This method continuously and autonomously learns from the system,effectively accumulating experiential knowledge for calibration strategies and demonstrating superior adaptability compared to traditional methods.In systems based on dispersion compensating fiber,micro-ring resonator array,and Mach-Zehnder interferometer array that use multiwavelength optical carriers as the light source,the DRC method enables the completion of the corresponding signal processing functions within 21 iterations.This method provides efficient and accurate control,making it suitable for applications such as optical convolution computation acceleration,microwave photonic signal processing,and optical network routing.展开更多
This study involved a comprehensive investigation aimed at achieving efficient multi-millijoule THz wave generation by exploiting the unique properties of cylindrical GaAs waveguides as effective mediators of the conv...This study involved a comprehensive investigation aimed at achieving efficient multi-millijoule THz wave generation by exploiting the unique properties of cylindrical GaAs waveguides as effective mediators of the conversion of laser energy into THz waves.Through meticulous investigation,valuable insights into optimizing THz generation processes for practical applications were unearthed.By investigating Hertz potentials,an eigen-value equation for the solutions of the guided modes(i.e.,eigenvalues)was found.The effects of various param-eters,including the effective mode index and the laser pulse power,on the electric field components of THz radia-tion,including the fundamental TE(transverse electric)and TM(transverse magnetic)modes,were evaluated.By analyzing these factors,this research elucidated the nuanced mechanisms governing THz wave generation within cylindrical GaAs waveguides,paving the way for refined methodologies and enhanced efficiency.The sig-nificance of cylindrical GaAs waveguides extends beyond their roles as mere facilitators of THz generation;their design and fabrication hold the key to unlocking the potential for compact and portable THz systems.This trans-formative capability not only amplifies the efficiency of THz generation but also broadens the horizons of practical applications.展开更多
In response to the issue of fuzzy matching and association when optical observation data are matched with the orbital elements in a catalog database,this paper proposes a matching and association strategy based on the...In response to the issue of fuzzy matching and association when optical observation data are matched with the orbital elements in a catalog database,this paper proposes a matching and association strategy based on the arcsegment difference method.First,a matching error threshold is set to match the observation data with the known catalog database.Second,the matching results for the same day are sorted on the basis of target identity and observation residuals.Different matching error thresholds and arc-segment dynamic association thresholds are then applied to categorize the observation residuals of the same target across different arc-segments,yielding matching results under various thresholds.Finally,the orbital residual is computed through orbit determination(OD),and the positional error is derived by comparing the OD results with the orbit track from the catalog database.The appropriate matching error threshold is then selected on the basis of these results,leading to the final matching and association of the fuzzy correlation data.Experimental results showed that the correct matching rate for data arc-segments is 92.34% when the matching error threshold is set to 720″,with the arc-segment difference method processing the results of an average matching rate of 97.62% within 8 days.The remaining 5.28% of the fuzzy correlation data are correctly matched and associated,enabling identification of orbital maneuver targets through further processing and analysis.This method substantially enhances the efficiency and accuracy of space target cataloging,offering robust technical support for dynamic maintenance of the space target database.展开更多
Wave mixing and the intricate optical interactions therein have traditionally been regarded as hallmarks of nonlinear optics.A quintessential example of wave mixing lies in the nonlocal triple correlation between the ...Wave mixing and the intricate optical interactions therein have traditionally been regarded as hallmarks of nonlinear optics.A quintessential example of wave mixing lies in the nonlocal triple correlation between the pump beam and the generated twin photons via spontaneous parametric down-conversion(SPDC).However,the SPDC process typically requires intense laser pumping and suffers from inherently low conversion efficiencies,necessitating single-photon detection.In this work,we establish that analogous triple correlations can be effectively produced using low-power continuous-wave illumination,achieved through a commercially available spatial light modulator(SLM)in a linear optical configuration.Specifically,we show how to spatially manipulate and customize this triple correlation and further investigate the applicability across diverse domains,including pattern recognition,intelligent nonlocal image processing,and sensitivity-enhanced optical metrology.Our findings establish,to our knowledge,a novel framework for classical,linear emulation of quantum and nonlinear optical information processing paradigms rooted in multi-wave mixing.展开更多
Point spread function(PSF)engineering has been pivotal in the remarkable progress made in high-resolution imaging in the last decades.However,the diversity in PSF structures attainable through existing engineering met...Point spread function(PSF)engineering has been pivotal in the remarkable progress made in high-resolution imaging in the last decades.However,the diversity in PSF structures attainable through existing engineering methods is limited.Here,we report universal PSF engineering,demonstrating a method to synthesize an arbitrary set of spatially varying 3D PSFs between the input and output volumes of a spatially incoherent diffractive processor composed of cascaded transmissive surfaces.We rigorously analyze the PSF engineering capabilities of such diffractive processors within the diffraction limit of light and provide numerical demonstrations of unique imaging capabilities,such as snapshot 3D multispectral imaging without involving any spectral filters,axial scanning or digital reconstruction steps,which is enabled by the spatial and spectral engineering of 3D PSFs.Our framework and analysis would be important for future advancements in computational imaging,sensing,and diffractive processing of 3D optical information.展开更多
For conventional optical polarization imaging of underwater target,the polarization degree of backscatter should be pre-measured by averaging the pixel intensities in the no target region of the polarization images,an...For conventional optical polarization imaging of underwater target,the polarization degree of backscatter should be pre-measured by averaging the pixel intensities in the no target region of the polarization images,and the polarization property of the target is assumed to be completely depolarized.When the scattering background is unseen in the field of view or the target is polarized,conventional method is helpless in detecting the target.An improvement is to use lots of co-polarization and cross polarization detection components.We propose a polarization subtraction method to estimate depolarization property of the scattering noise and target signal.And experiment in a quartz cuvette container is performed to demonstrate the effectiveness of the proposed method.The results show that the proposed method can work without scattering background reference,and further recover the target along with smooth surface for polarization preserving response.This study promotes the development of optical polarization imaging systems in underwater environments.展开更多
Equalization can compensate channel distortion caused by channel multipath effects, and effectively improve convergent of modulation constellation diagram in optical wireless system. In this paper, the subspace blind ...Equalization can compensate channel distortion caused by channel multipath effects, and effectively improve convergent of modulation constellation diagram in optical wireless system. In this paper, the subspace blind equalization algorithm is used to preprocess M-ary phase shift keying(MPSK) subcarrier modulation signal in receiver. Mountain clustering is adopted to get the clustering centers of MPSK modulation constellation diagram, and the modulation order is automatically identified through the k-nearest neighbor(KNN) classifier. The experiment has been done under four different weather conditions. Experimental results show that the convergent of constellation diagram is improved effectively after using the subspace blind equalization algorithm, which means that the accuracy of modulation recognition is increased. The correct recognition rate of 16 PSK can be up to 85% in any kind of weather condition which is mentioned in paper. Meanwhile, the correct recognition rate is the highest in cloudy and the lowest in heavy rain condition.展开更多
An optical time-domain differentiation scheme is proposed and demonstrated based on the intensive differential group delay in a high birefringence fibre waveguide. Results show that the differentiation waveforms agree...An optical time-domain differentiation scheme is proposed and demonstrated based on the intensive differential group delay in a high birefringence fibre waveguide. Results show that the differentiation waveforms agree well with the mathematically calculated derivatives. Both error and efficiency will increase when the birefringence fibre becomes longer, and the error rises up more quickly while the efficiency approaches to a maximum of ~0.25. By using a 1-m birefringence fibre a lower error of ~0.26% is obtained with an efficiency of 1% for the first-order differentiation of 10-ps Gaussian optical pulses, and the high-order optical differentiation up to 4th order is achieved with an error less than 3%. Due to its compact structure being easy to integrate and cascade into photonic circuits, our scheme has great potential for ultrafast signal processing.展开更多
Non-Hermitian systems have observed numerous novel phenomena and might lead to various applications.Unlike standard quantum physics,the conservation of energy guaranteed by the closed system is broken in the non-Hermi...Non-Hermitian systems have observed numerous novel phenomena and might lead to various applications.Unlike standard quantum physics,the conservation of energy guaranteed by the closed system is broken in the non-Hermitian system,and the energy can be exchanged between the system and the environment.Here we present a scheme for simulating the dissipative phase transition with an open quantum optical system.The competition between the coherent interaction and dissipation leads to the second-order phase transition.Furthermore,the quantum correlation in terms of squeezing is studied around the critical point.Our work may provide a new route to explore the non-Hermitian quantum physics with feasible techniques in experiments.展开更多
The principle and charecteristics of verious digital optical signal amplifiers using Er doped fiber optical bistability devices have been discussed. Optical signal gain and its variation with the parameters of the de...The principle and charecteristics of verious digital optical signal amplifiers using Er doped fiber optical bistability devices have been discussed. Optical signal gain and its variation with the parameters of the devices with constant or pulse optical bias have been calculated, and the design principle of those devices has been given.展开更多
A high-speed and high-resolution optical A/D quantizer is proposed.Its architecture is discussed.Bit circuits are built by using the phase modulators in parallel.Based on the different character of the half-wave volta...A high-speed and high-resolution optical A/D quantizer is proposed.Its architecture is discussed.Bit circuits are built by using the phase modulators in parallel.Based on the different character of the half-wave voltage for every phase modulator and the polarized bias design of incident light,the RF input signal is coled and transmitted in the form of optical digital signal.According to the principle of the architecture,the high-resolution quantizers with 8-bit and 12-bit,et al.are built,which operate at 100 GS/s.Their quantization noise is invariable almost with bit circuits increasing.The simulation result of 4-bit A/D quantizer is also given.展开更多
The output characteristics of nonlinear optical fiber-loop mirror are analyzed in detail when the pump pulses with the same wavelength are input in the both directions for recovering the clock component of the signal ...The output characteristics of nonlinear optical fiber-loop mirror are analyzed in detail when the pump pulses with the same wavelength are input in the both directions for recovering the clock component of the signal spectrum.It is found that the double output pulses are produced in the transmission port of the nonlinear optical fiber-loop mirror.The output pulse peaks are located in time domain at the rising and falling edges of the pump pulses.It is demonstrated that the rising and falling edges of the pump pulse can be directly extracted by this method.Through numerical simulation,the effects of therelative delay of pump pulses and the dispersion of fiber on the characteristics of output pulses are studied.By spectrum analysis,it is found that the spectrum of output pulse sequence includes the clock components of the pump pulse sequence,and a new idea is provided for all-optical clock extraction.展开更多
In this paper, Recurrence Quantification Analysis (RQA) is set as a practical nonlinear data tool to establish and compare surface roughness (Ra) through percentage parameters of a dynamical system: Recurrence (%REC),...In this paper, Recurrence Quantification Analysis (RQA) is set as a practical nonlinear data tool to establish and compare surface roughness (Ra) through percentage parameters of a dynamical system: Recurrence (%REC), Determinism (%DET) and Laminarity (%LAM). Variations in surface roughness of different machining procedures from a typical metallic casting comparator are obtained from scattering intensity of a laser beam and expressed as changes in the statistics of speckle patterns and profiles optical properties. The application of the analysis (RQA) by Recurrence Plots (RPs), allowed to distinguish between machining procedures, highlighting features that other methods are unable to detect.展开更多
Owing to the unique feature that the signal and reference waves of self-interference digital holography(SIDH)contain the same spatial information from the same point of object,compared with conventional digital hologr...Owing to the unique feature that the signal and reference waves of self-interference digital holography(SIDH)contain the same spatial information from the same point of object,compared with conventional digital holography,the SIDH has the special spatial coherence properties.We present a statistical optics approach to analyzing the formation of cross-correlation image in SIDH.Our study reveals that the spatial coherence of illumination light can greatly influence the imaging characteristics of SIDH,and the impact extent of the spatial coherence depends substantially on the recording distance of hologram.The theoretical conclusions are supported well by numerical simulation and optical experiments.展开更多
A fully convolutional encoder-decoder network(FCEDN),a deep learning model,was developed and applied to image scanning microscopy(ISM).Super-resolution imaging was achieved with a 78μm×78μm field of view and 12...A fully convolutional encoder-decoder network(FCEDN),a deep learning model,was developed and applied to image scanning microscopy(ISM).Super-resolution imaging was achieved with a 78μm×78μm field of view and 12.5 Hz-40 Hz imaging frequency.Mono and dual-color continuous super-resolution images of microtubules and cargo in cells were obtained by ISM.The signal-to-noise ratio of the obtained images was improved from 3.94 to 22.81 and the positioning accuracy of cargoes was enhanced by FCEDN from 15.83±2.79 nm to 2.83±0.83 nm.As a general image enhancement method,FCEDN can be applied to various types of microscopy systems.Application with conventional spinning disk confocal microscopy was demonstrated and significantly improved images were obtained.展开更多
We present an imaging approach via sparsity constraint and sparse speckle illumination which can dramatically en- hance the optical system＇s imaging resolution. When the object is illuminated by some sparse speckles ...We present an imaging approach via sparsity constraint and sparse speckle illumination which can dramatically en- hance the optical system＇s imaging resolution. When the object is illuminated by some sparse speckles and the sparse reconstruction algorithm is utilized to restore the blur image, numerical simulated results demonstrate that the image, whose resolution exceeds the Rayleigh limit, can be stably reconstructed even if the detection signal-to-noise ratio （SNR） is less than 10 dB. Factors affecting the quality of the reconstructed image, such as the coded pattern＇s sparsity and the detection SNR, are also studied,展开更多
文摘Incoherent optical processing of microwave signals,where low-coherence broadband light sources are employed instead of costly mode locked lasers,has attracted great interest thanks to its wide applications in microwave photonics filtering[1–3],arbitrary generation[4–6]and analog to digital conversion[7]。
文摘A hybrid fiber optical bistable device with electrical feedback has been proposed and analyzed.Bistability operation and some applications for optical signal processing have been realized experimentally .
文摘We propose a novel all-optical sampling method using nonlinear polarization rotation in a semiconductor optical amplifier. A rate-equation model capable of describing the all-optical sampling mechanism is presented in this paper. Based on this model, we investigate the optimized operating parameters of the proposed system by simulating the output intensity of the probe light as functions of the input polarization angle, the phase induced by the polarization controller, and the ori- entation of the polarization beam splitter. The simulated results show that we can obtain a good linear slope and a large linear dynamic range,which is suitable for all-optical sampling. The operating power of the pump light can be less than lmW. The presented all-optical sampling method can potentially operate at a sampling rate up to hundreds GS/s and needs low optical power.
基金the National Natural Science Foundation of China(62302504,11902358).
文摘Multi-wavelength optical information processing systems are commonly utilized in optical neural networks and broadband signal processing.However,their effectiveness is often compromised by frequency-selective responses caused by fabrication,transmission,and environmental factors.To mitigate these issues,this study introduces a deep reinforcement learning calibration(DRC)method inspired by the deep deterministic policy gradient training strategy.This method continuously and autonomously learns from the system,effectively accumulating experiential knowledge for calibration strategies and demonstrating superior adaptability compared to traditional methods.In systems based on dispersion compensating fiber,micro-ring resonator array,and Mach-Zehnder interferometer array that use multiwavelength optical carriers as the light source,the DRC method enables the completion of the corresponding signal processing functions within 21 iterations.This method provides efficient and accurate control,making it suitable for applications such as optical convolution computation acceleration,microwave photonic signal processing,and optical network routing.
文摘This study involved a comprehensive investigation aimed at achieving efficient multi-millijoule THz wave generation by exploiting the unique properties of cylindrical GaAs waveguides as effective mediators of the conversion of laser energy into THz waves.Through meticulous investigation,valuable insights into optimizing THz generation processes for practical applications were unearthed.By investigating Hertz potentials,an eigen-value equation for the solutions of the guided modes(i.e.,eigenvalues)was found.The effects of various param-eters,including the effective mode index and the laser pulse power,on the electric field components of THz radia-tion,including the fundamental TE(transverse electric)and TM(transverse magnetic)modes,were evaluated.By analyzing these factors,this research elucidated the nuanced mechanisms governing THz wave generation within cylindrical GaAs waveguides,paving the way for refined methodologies and enhanced efficiency.The sig-nificance of cylindrical GaAs waveguides extends beyond their roles as mere facilitators of THz generation;their design and fabrication hold the key to unlocking the potential for compact and portable THz systems.This trans-formative capability not only amplifies the efficiency of THz generation but also broadens the horizons of practical applications.
基金supported by National Natural Science Foundation of China(12273080).
文摘In response to the issue of fuzzy matching and association when optical observation data are matched with the orbital elements in a catalog database,this paper proposes a matching and association strategy based on the arcsegment difference method.First,a matching error threshold is set to match the observation data with the known catalog database.Second,the matching results for the same day are sorted on the basis of target identity and observation residuals.Different matching error thresholds and arc-segment dynamic association thresholds are then applied to categorize the observation residuals of the same target across different arc-segments,yielding matching results under various thresholds.Finally,the orbital residual is computed through orbit determination(OD),and the positional error is derived by comparing the OD results with the orbit track from the catalog database.The appropriate matching error threshold is then selected on the basis of these results,leading to the final matching and association of the fuzzy correlation data.Experimental results showed that the correct matching rate for data arc-segments is 92.34% when the matching error threshold is set to 720″,with the arc-segment difference method processing the results of an average matching rate of 97.62% within 8 days.The remaining 5.28% of the fuzzy correlation data are correctly matched and associated,enabling identification of orbital maneuver targets through further processing and analysis.This method substantially enhances the efficiency and accuracy of space target cataloging,offering robust technical support for dynamic maintenance of the space target database.
基金National Natural Science Foundation of China(12274037,11735005,11654003,61675028)Science and Technology Development Fund from Macao SAR(FDCT)(0105/2023/RIA2)Interdiscipline Research Funds of Beijing Normal University。
文摘Wave mixing and the intricate optical interactions therein have traditionally been regarded as hallmarks of nonlinear optics.A quintessential example of wave mixing lies in the nonlocal triple correlation between the pump beam and the generated twin photons via spontaneous parametric down-conversion(SPDC).However,the SPDC process typically requires intense laser pumping and suffers from inherently low conversion efficiencies,necessitating single-photon detection.In this work,we establish that analogous triple correlations can be effectively produced using low-power continuous-wave illumination,achieved through a commercially available spatial light modulator(SLM)in a linear optical configuration.Specifically,we show how to spatially manipulate and customize this triple correlation and further investigate the applicability across diverse domains,including pattern recognition,intelligent nonlocal image processing,and sensitivity-enhanced optical metrology.Our findings establish,to our knowledge,a novel framework for classical,linear emulation of quantum and nonlinear optical information processing paradigms rooted in multi-wave mixing.
文摘Point spread function(PSF)engineering has been pivotal in the remarkable progress made in high-resolution imaging in the last decades.However,the diversity in PSF structures attainable through existing engineering methods is limited.Here,we report universal PSF engineering,demonstrating a method to synthesize an arbitrary set of spatially varying 3D PSFs between the input and output volumes of a spatially incoherent diffractive processor composed of cascaded transmissive surfaces.We rigorously analyze the PSF engineering capabilities of such diffractive processors within the diffraction limit of light and provide numerical demonstrations of unique imaging capabilities,such as snapshot 3D multispectral imaging without involving any spectral filters,axial scanning or digital reconstruction steps,which is enabled by the spatial and spectral engineering of 3D PSFs.Our framework and analysis would be important for future advancements in computational imaging,sensing,and diffractive processing of 3D optical information.
基金National Natural Science Foundation of China(Nos.11847069,11847127)Science Foundation of North University of China(No.XJJ20180030)。
文摘For conventional optical polarization imaging of underwater target,the polarization degree of backscatter should be pre-measured by averaging the pixel intensities in the no target region of the polarization images,and the polarization property of the target is assumed to be completely depolarized.When the scattering background is unseen in the field of view or the target is polarized,conventional method is helpless in detecting the target.An improvement is to use lots of co-polarization and cross polarization detection components.We propose a polarization subtraction method to estimate depolarization property of the scattering noise and target signal.And experiment in a quartz cuvette container is performed to demonstrate the effectiveness of the proposed method.The results show that the proposed method can work without scattering background reference,and further recover the target along with smooth surface for polarization preserving response.This study promotes the development of optical polarization imaging systems in underwater environments.
基金supported by the National Natural Science Foundation of China(No.61671375)the Industrial Research of Science and Technology Plan of Shaanxi Province(No.2016GY-082)
文摘Equalization can compensate channel distortion caused by channel multipath effects, and effectively improve convergent of modulation constellation diagram in optical wireless system. In this paper, the subspace blind equalization algorithm is used to preprocess M-ary phase shift keying(MPSK) subcarrier modulation signal in receiver. Mountain clustering is adopted to get the clustering centers of MPSK modulation constellation diagram, and the modulation order is automatically identified through the k-nearest neighbor(KNN) classifier. The experiment has been done under four different weather conditions. Experimental results show that the convergent of constellation diagram is improved effectively after using the subspace blind equalization algorithm, which means that the accuracy of modulation recognition is increased. The correct recognition rate of 16 PSK can be up to 85% in any kind of weather condition which is mentioned in paper. Meanwhile, the correct recognition rate is the highest in cloudy and the lowest in heavy rain condition.
基金supported by the National Natural Science Foundation of China (Grant Nos. 60907027 and 60877057)the Specialized Research Fund for the Doctoral Program of Higher Education of Ministry of Education of China (Grant No. 20090009120035)
文摘An optical time-domain differentiation scheme is proposed and demonstrated based on the intensive differential group delay in a high birefringence fibre waveguide. Results show that the differentiation waveforms agree well with the mathematically calculated derivatives. Both error and efficiency will increase when the birefringence fibre becomes longer, and the error rises up more quickly while the efficiency approaches to a maximum of ~0.25. By using a 1-m birefringence fibre a lower error of ~0.26% is obtained with an efficiency of 1% for the first-order differentiation of 10-ps Gaussian optical pulses, and the high-order optical differentiation up to 4th order is achieved with an error less than 3%. Due to its compact structure being easy to integrate and cascade into photonic circuits, our scheme has great potential for ultrafast signal processing.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 61925503, 11874038, and 11654002)the Key Project of the National Key R&D Program of China (Grant Nos. 2016YFA0301402 and 2020YFA0309400)+2 种基金the Program for the Innovative Talents of Higher Education Institutions of Shanxithe Program for Sanjin Scholars of Shanxi Provincethe Fund for Shanxi “1331 Project” Key Subjects Construction
文摘Non-Hermitian systems have observed numerous novel phenomena and might lead to various applications.Unlike standard quantum physics,the conservation of energy guaranteed by the closed system is broken in the non-Hermitian system,and the energy can be exchanged between the system and the environment.Here we present a scheme for simulating the dissipative phase transition with an open quantum optical system.The competition between the coherent interaction and dissipation leads to the second-order phase transition.Furthermore,the quantum correlation in terms of squeezing is studied around the critical point.Our work may provide a new route to explore the non-Hermitian quantum physics with feasible techniques in experiments.
文摘The principle and charecteristics of verious digital optical signal amplifiers using Er doped fiber optical bistability devices have been discussed. Optical signal gain and its variation with the parameters of the devices with constant or pulse optical bias have been calculated, and the design principle of those devices has been given.
基金Natural Science Foundation from Colleges and Universities of Jiangsu Province(04KJD140033)
文摘A high-speed and high-resolution optical A/D quantizer is proposed.Its architecture is discussed.Bit circuits are built by using the phase modulators in parallel.Based on the different character of the half-wave voltage for every phase modulator and the polarized bias design of incident light,the RF input signal is coled and transmitted in the form of optical digital signal.According to the principle of the architecture,the high-resolution quantizers with 8-bit and 12-bit,et al.are built,which operate at 100 GS/s.Their quantization noise is invariable almost with bit circuits increasing.The simulation result of 4-bit A/D quantizer is also given.
基金supported by the National High Technology Research and Development Program of China(No.2009AA01Z216)the Major State Basic Research and Development Program of China(No.2011CB301703)
文摘The output characteristics of nonlinear optical fiber-loop mirror are analyzed in detail when the pump pulses with the same wavelength are input in the both directions for recovering the clock component of the signal spectrum.It is found that the double output pulses are produced in the transmission port of the nonlinear optical fiber-loop mirror.The output pulse peaks are located in time domain at the rising and falling edges of the pump pulses.It is demonstrated that the rising and falling edges of the pump pulse can be directly extracted by this method.Through numerical simulation,the effects of therelative delay of pump pulses and the dispersion of fiber on the characteristics of output pulses are studied.By spectrum analysis,it is found that the spectrum of output pulse sequence includes the clock components of the pump pulse sequence,and a new idea is provided for all-optical clock extraction.
文摘In this paper, Recurrence Quantification Analysis (RQA) is set as a practical nonlinear data tool to establish and compare surface roughness (Ra) through percentage parameters of a dynamical system: Recurrence (%REC), Determinism (%DET) and Laminarity (%LAM). Variations in surface roughness of different machining procedures from a typical metallic casting comparator are obtained from scattering intensity of a laser beam and expressed as changes in the statistics of speckle patterns and profiles optical properties. The application of the analysis (RQA) by Recurrence Plots (RPs), allowed to distinguish between machining procedures, highlighting features that other methods are unable to detect.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.91750202,91750114,and 11922406)the National Key Research and Development Program of China(Grant Nos.2018YFA0306200 and 2017YFA0303700)the Science and Technology Project of Jiangxi Provincial Education Department,China(Grant No.GJJ190915).
文摘Owing to the unique feature that the signal and reference waves of self-interference digital holography(SIDH)contain the same spatial information from the same point of object,compared with conventional digital holography,the SIDH has the special spatial coherence properties.We present a statistical optics approach to analyzing the formation of cross-correlation image in SIDH.Our study reveals that the spatial coherence of illumination light can greatly influence the imaging characteristics of SIDH,and the impact extent of the spatial coherence depends substantially on the recording distance of hologram.The theoretical conclusions are supported well by numerical simulation and optical experiments.
基金Project supported by the China Postdoctoral Science Foundation,the National Key Research and Development Program of China for Y.S.(Grant No.2017YFA0505300)the National Science Foundation of China for Y.S.(Grant No.21825401)。
文摘A fully convolutional encoder-decoder network(FCEDN),a deep learning model,was developed and applied to image scanning microscopy(ISM).Super-resolution imaging was achieved with a 78μm×78μm field of view and 12.5 Hz-40 Hz imaging frequency.Mono and dual-color continuous super-resolution images of microtubules and cargo in cells were obtained by ISM.The signal-to-noise ratio of the obtained images was improved from 3.94 to 22.81 and the positioning accuracy of cargoes was enhanced by FCEDN from 15.83±2.79 nm to 2.83±0.83 nm.As a general image enhancement method,FCEDN can be applied to various types of microscopy systems.Application with conventional spinning disk confocal microscopy was demonstrated and significantly improved images were obtained.
基金Project supported by the National Natural Science Foundation of China(Grant No.61571427)
文摘We present an imaging approach via sparsity constraint and sparse speckle illumination which can dramatically en- hance the optical system＇s imaging resolution. When the object is illuminated by some sparse speckles and the sparse reconstruction algorithm is utilized to restore the blur image, numerical simulated results demonstrate that the image, whose resolution exceeds the Rayleigh limit, can be stably reconstructed even if the detection signal-to-noise ratio （SNR） is less than 10 dB. Factors affecting the quality of the reconstructed image, such as the coded pattern＇s sparsity and the detection SNR, are also studied,
