In recent years,space-division multiplexing(SDM)technology,which involves transmitting data information on multiple parallel channels for efficient capacity scaling,has been widely used in fiber and free-space optical...In recent years,space-division multiplexing(SDM)technology,which involves transmitting data information on multiple parallel channels for efficient capacity scaling,has been widely used in fiber and free-space optical communication sys-tems.To enable flexible data management and cope with the mixing between different channels,the integrated reconfig-urable optical processor is used for optical switching and mitigating the channel crosstalk.However,efficient online train-ing becomes intricate and challenging,particularly when dealing with a significant number of channels.Here we use the stochastic parallel gradient descent(SPGD)algorithm to configure the integrated optical processor,which has less com-putation than the traditional gradient descent(GD)algorithm.We design and fabricate a 6×6 on-chip optical processor on silicon platform to implement optical switching and descrambling assisted by the online training with the SPDG algorithm.Moreover,we apply the on-chip processor configured by the SPGD algorithm to optical communications for optical switching and efficiently mitigating the channel crosstalk in SDM systems.In comparison with the traditional GD al-gorithm,it is found that the SPGD algorithm features better performance especially when the scale of matrix is large,which means it has the potential to optimize large-scale optical matrix computation acceleration chips.展开更多
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
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
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 .
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
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
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
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
A novel approach to extract flame fronts, which is called the conditioned level-set method with block division (CLSB), has been developed. Based on a two-phase level-set formulation, the conditioned initialization a...A novel approach to extract flame fronts, which is called the conditioned level-set method with block division (CLSB), has been developed. Based on a two-phase level-set formulation, the conditioned initialization and region-lock optimiza-tion appear to be beneficial to improve the efficiency and accuracy of the flame contour identification. The original block- division strategy enables the approach to be unsupervised by calculating local self-adaptive threshold values autonomously before binarization. The CLSB approach has been applied to deal with a large set of experimental data involving swirl- stabilized premixed combustion in diluted regimes operating at atmospheric pressures. The OH-PLIF measurements have been carried out in this framework. The resulting images are, thus, featured by lower signal-to-noise ratios (SNRs) than the ideal image; relatively complex flame structures lead to significant non-uniformity in the OH signal intensity; and, the mag- nitude of the maximum OH gradient observed along the flame front can also vary depending on flow or local stoichiometry. Compared with other conventional edge detection operators, the CLSB method demonstrates a good ability to deal with the OH-PLIF images at low SNR and with the presence of a multiple scales of both OH intensity and OH gradient. The robustness to noise sensitivity and intensity inhomogeneity has been evaluated throughout a range of experimental images of diluted flames, as well as against a circle test as Ground Truth (GT).展开更多
An adaptive optics (AO) system based on a stochastic parallel gradient descent (SPGD) algorithm is proposed to reduce the speckle noises in the optical system of a stellar coronagraph in order to further improve t...An adaptive optics (AO) system based on a stochastic parallel gradient descent (SPGD) algorithm is proposed to reduce the speckle noises in the optical system of a stellar coronagraph in order to further improve the contrast. The principle of the SPGD algorithm is described briefly and a metric suitable for point source imaging optimization is given. The feasibility and good performance of the SPGD algorithm is demonstrated by an experimental system featured with a 140-actuator deformable mirror and a Hartrnann-Shark wavefront sensor. Then the SPGD based AO is applied to a liquid crystal array (LCA) based coronagraph to improve the contrast. The LCA can modulate the incoming light to generate a pupil apodization mask of any pattern. A circular stepped pattern is used in our preliminary experiment and the image contrast shows improvement from 10^-3 to 10^-4.5 at an angular distance of 2A/D after being corrected by SPGD based AO.展开更多
History, present situation and importancy of the laser-generated ultrasonic technique are presented. Basic principles and some experimental results of laser ultrasonic generation and optical detection and processing a...History, present situation and importancy of the laser-generated ultrasonic technique are presented. Basic principles and some experimental results of laser ultrasonic generation and optical detection and processing are discussed. Several problems about applying this technique to NDT are also discussed in this paper.展开更多
We express a photonic packet switch prototype based on optical label processing methods which dramatically increase the label processing capability. We experimentally demonstrate 40Gbit/s/port packet switching and opt...We express a photonic packet switch prototype based on optical label processing methods which dramatically increase the label processing capability. We experimentally demonstrate 40Gbit/s/port packet switching and optical buffering capabilities of the prototype.展开更多
Bragg processing using a volume hologram offers an alternative in optical image processing in contrast to Fourier-plane processing. By placing a volume hologram near the object in an optical imaging setup, we achieve ...Bragg processing using a volume hologram offers an alternative in optical image processing in contrast to Fourier-plane processing. By placing a volume hologram near the object in an optical imaging setup, we achieve Bragg processing. In this review, we discuss various image processing methods achievable with acousto-optic modulators as dynamic and programmable volume holograms. In particular, we concentrate on the discussion of various differentiation operations leading to edge extraction capabilities.展开更多
An effective theoretical analysis method is presented to analyze different linear optical signal processing functions with optical fikers reported in literatures. For different applications, the optical filters are su...An effective theoretical analysis method is presented to analyze different linear optical signal processing functions with optical fikers reported in literatures. For different applications, the optical filters are supposed to operate on the analog or digital part of the signal separately, namely analog spectrum conversion and digital spectrum conversion. For instance, the return-to-zero (RZ) to non-return-to-zero (NRZ) format conversion for intensity or phase modulated signals are based on the analog spectrum conversion process, while the (N)RZ to (N)RZ phase-shift-keying (PSK) format conversion, logic NOT gate and clock recovery for RZ signals are based on the digital spectrum conversion process. Theoretical analyses with the help of numerical simulation are used to verify the reported experimental results, and all the experimental results can be effectively analyzed with this analytical model. The effect of the transmission spectrum of the filter on the performance of the converted signal is investigated. The most important factor is that the theoretical analysis provides an effective way to optimize the optical filter for different optical signal processing functions.展开更多
The angular method(AS)cannot be used in long-distance propagation because it produces severe numerical errors due to the sampling problem in the transfer function.Two ways can solve this problem in AS for long-distanc...The angular method(AS)cannot be used in long-distance propagation because it produces severe numerical errors due to the sampling problem in the transfer function.Two ways can solve this problem in AS for long-distance propagation.One is zero-padding to make sure that the calculation window is wide enough,but it leads to a huge calculation burden.The other is a method called band-limited angular spectrum(BLAS),in which the transfer function is truncated and results in that the calculation accuracy decreases as the propagation distance increases.In this paper,a new method called modified scaling angular spectrum(MSAS)to solve the problem for long-distance propagation is proposed.A scaling factor is introduced in MSAS so that the sampling interval of the input plane can be adjusted arbitrarily unlike AS whose sampling interval is restricted by the detector’s pixel size.The sampling interval of the input plane is larger than the detector’s pixel size so the size of calculation window suitable for long-distance field propagation in the input plane is smaller than the size of the calculation window required by the zero-padding.Therefore,the method reduces the calculation redundancy and improves the calculation speed.The results from simulations and experiments show that MSAS has a good signal-to-noise ratio(SNR),and the calculation accuracy of MSAS is better than BLAS.展开更多
Algorithms for reconstruction of linear and circular birefringence-dichroism of optically thin anisotropic biological layers are presented.The technique of Jones matrix tomography of poly-crystalline films of biologic...Algorithms for reconstruction of linear and circular birefringence-dichroism of optically thin anisotropic biological layers are presented.The technique of Jones matrix tomography of poly-crystalline films of biological fuids of various human organs has been developed and experimentally tested.The coordinate distributions of phase and amplitude anisotropy of bile films and synovial fuid taken from the knee joint are determined and statistically analyzed.Criteria(statistical moments of 3rd and 4th orders)of differential diagnostics of early stages of cholelithiasis and septic arthritis of the knee joint with excellent balanced accuracy were determined.Data on the diagnostic fficiency of the Jones matrix tomography method for polyerystalline plasma(liver disease),urine(albuminuria)and cytological smears(cervical cancer)are presented.展开更多
Super-continuum (SC) generated from optical fibers has many attractive applications in optical communication systems. Discussing the mechanism of wideband and flat SC generation, we describe all-optical signal process...Super-continuum (SC) generated from optical fibers has many attractive applications in optical communication systems. Discussing the mechanism of wideband and flat SC generation, we describe all-optical signal processing that employs the SC.展开更多
It is striking that the quantum Zeno effect can be used to launch a direct counterfactual communication between two spatially separated parties, Alice and Bob. So far, existing protocols of this type only provide a de...It is striking that the quantum Zeno effect can be used to launch a direct counterfactual communication between two spatially separated parties, Alice and Bob. So far, existing protocols of this type only provide a deterministic counterfactual communication service. However, this counterfactuality should be payed at a price. Firstly, the transmission time is much longer than a classical transmission costs. Secondly, the chained-cycle structure makes them more sensitive to channel noises. Here, we extend the idea of counterfactual communication, and present a probabilistic-counterfactual quantum communication protocol, which is proved to have advantages over the deterministic ones. Moreover, the presented protocol could evolve to a deterministic one solely by adjusting the parameters of the beam splitters.展开更多
基金supported by the National Natural Science Foundation of China(NSFC)(62125503,62261160388)the Natural Science Foundation of Hubei Province of China(2023AFA028)the Innovation Project of Optics Valley Laboratory(OVL2021BG004).
文摘In recent years,space-division multiplexing(SDM)technology,which involves transmitting data information on multiple parallel channels for efficient capacity scaling,has been widely used in fiber and free-space optical communication sys-tems.To enable flexible data management and cope with the mixing between different channels,the integrated reconfig-urable optical processor is used for optical switching and mitigating the channel crosstalk.However,efficient online train-ing becomes intricate and challenging,particularly when dealing with a significant number of channels.Here we use the stochastic parallel gradient descent(SPGD)algorithm to configure the integrated optical processor,which has less com-putation than the traditional gradient descent(GD)algorithm.We design and fabricate a 6×6 on-chip optical processor on silicon platform to implement optical switching and descrambling assisted by the online training with the SPDG algorithm.Moreover,we apply the on-chip processor configured by the SPGD algorithm to optical communications for optical switching and efficiently mitigating the channel crosstalk in SDM systems.In comparison with the traditional GD al-gorithm,it is found that the SPGD algorithm features better performance especially when the scale of matrix is large,which means it has the potential to optimize large-scale optical matrix computation acceleration chips.
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]。
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.
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 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,
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.
文摘A novel approach to extract flame fronts, which is called the conditioned level-set method with block division (CLSB), has been developed. Based on a two-phase level-set formulation, the conditioned initialization and region-lock optimiza-tion appear to be beneficial to improve the efficiency and accuracy of the flame contour identification. The original block- division strategy enables the approach to be unsupervised by calculating local self-adaptive threshold values autonomously before binarization. The CLSB approach has been applied to deal with a large set of experimental data involving swirl- stabilized premixed combustion in diluted regimes operating at atmospheric pressures. The OH-PLIF measurements have been carried out in this framework. The resulting images are, thus, featured by lower signal-to-noise ratios (SNRs) than the ideal image; relatively complex flame structures lead to significant non-uniformity in the OH signal intensity; and, the mag- nitude of the maximum OH gradient observed along the flame front can also vary depending on flow or local stoichiometry. Compared with other conventional edge detection operators, the CLSB method demonstrates a good ability to deal with the OH-PLIF images at low SNR and with the presence of a multiple scales of both OH intensity and OH gradient. The robustness to noise sensitivity and intensity inhomogeneity has been evaluated throughout a range of experimental images of diluted flames, as well as against a circle test as Ground Truth (GT).
基金Supported by the National Natural Science Foundation of China(Grant Nos. 10873024 and 11003031)supported by the National Science Foundation under Grant ATM-0841440
文摘An adaptive optics (AO) system based on a stochastic parallel gradient descent (SPGD) algorithm is proposed to reduce the speckle noises in the optical system of a stellar coronagraph in order to further improve the contrast. The principle of the SPGD algorithm is described briefly and a metric suitable for point source imaging optimization is given. The feasibility and good performance of the SPGD algorithm is demonstrated by an experimental system featured with a 140-actuator deformable mirror and a Hartrnann-Shark wavefront sensor. Then the SPGD based AO is applied to a liquid crystal array (LCA) based coronagraph to improve the contrast. The LCA can modulate the incoming light to generate a pupil apodization mask of any pattern. A circular stepped pattern is used in our preliminary experiment and the image contrast shows improvement from 10^-3 to 10^-4.5 at an angular distance of 2A/D after being corrected by SPGD based AO.
文摘History, present situation and importancy of the laser-generated ultrasonic technique are presented. Basic principles and some experimental results of laser ultrasonic generation and optical detection and processing are discussed. Several problems about applying this technique to NDT are also discussed in this paper.
文摘We express a photonic packet switch prototype based on optical label processing methods which dramatically increase the label processing capability. We experimentally demonstrate 40Gbit/s/port packet switching and optical buffering capabilities of the prototype.
基金The work was supported by the National Natural Science Foundation of China(Nos.11762009 and 61865007)the Natural Science Foundation of Yunnan Province,China(No.2018FB101)+1 种基金the Key Program of Science and Technology of Yunnan Province(No.2019FA025)the Yunnan Provincial Program for Foreign Talent(No.104126760027)。
文摘Bragg processing using a volume hologram offers an alternative in optical image processing in contrast to Fourier-plane processing. By placing a volume hologram near the object in an optical imaging setup, we achieve Bragg processing. In this review, we discuss various image processing methods achievable with acousto-optic modulators as dynamic and programmable volume holograms. In particular, we concentrate on the discussion of various differentiation operations leading to edge extraction capabilities.
基金Acknowledgements The authors would like to thank Prof. Jos6 Azafia from INRS in Canada for helpful suggestions in preparing the manuscript. This work was supported in part by the National Basic Research Program of China (No. 2011CB301704), the Nature Science Fund for Distinguished Young Scholars (No. 61125501), the National Natural Science Foundation of China (NSFC) Major International Joint Research Project (Grant No. 61320106016) and Foundation for Innovative Research Groups of the Natural Science Foundation of Hubei Province (No. 2014CFA004).
文摘An effective theoretical analysis method is presented to analyze different linear optical signal processing functions with optical fikers reported in literatures. For different applications, the optical filters are supposed to operate on the analog or digital part of the signal separately, namely analog spectrum conversion and digital spectrum conversion. For instance, the return-to-zero (RZ) to non-return-to-zero (NRZ) format conversion for intensity or phase modulated signals are based on the analog spectrum conversion process, while the (N)RZ to (N)RZ phase-shift-keying (PSK) format conversion, logic NOT gate and clock recovery for RZ signals are based on the digital spectrum conversion process. Theoretical analyses with the help of numerical simulation are used to verify the reported experimental results, and all the experimental results can be effectively analyzed with this analytical model. The effect of the transmission spectrum of the filter on the performance of the converted signal is investigated. The most important factor is that the theoretical analysis provides an effective way to optimize the optical filter for different optical signal processing functions.
基金Project supported by the National Natural Science Foundation of China(Grant No.61705254)the Key Research and Development Program of Shaanxi Province of China(Grant No.2020GY-114).
文摘The angular method(AS)cannot be used in long-distance propagation because it produces severe numerical errors due to the sampling problem in the transfer function.Two ways can solve this problem in AS for long-distance propagation.One is zero-padding to make sure that the calculation window is wide enough,but it leads to a huge calculation burden.The other is a method called band-limited angular spectrum(BLAS),in which the transfer function is truncated and results in that the calculation accuracy decreases as the propagation distance increases.In this paper,a new method called modified scaling angular spectrum(MSAS)to solve the problem for long-distance propagation is proposed.A scaling factor is introduced in MSAS so that the sampling interval of the input plane can be adjusted arbitrarily unlike AS whose sampling interval is restricted by the detector’s pixel size.The sampling interval of the input plane is larger than the detector’s pixel size so the size of calculation window suitable for long-distance field propagation in the input plane is smaller than the size of the calculation window required by the zero-padding.Therefore,the method reduces the calculation redundancy and improves the calculation speed.The results from simulations and experiments show that MSAS has a good signal-to-noise ratio(SNR),and the calculation accuracy of MSAS is better than BLAS.
基金support of the Academy of Finland(grant projects:311698)support of INFOTECH grant project,as well as the MEPhI Academic Excellence Project(Contract No.02.a03.21.0005)the National Research Tomsk State University Academic D.I.Mendeleev Fund Program.
文摘Algorithms for reconstruction of linear and circular birefringence-dichroism of optically thin anisotropic biological layers are presented.The technique of Jones matrix tomography of poly-crystalline films of biological fuids of various human organs has been developed and experimentally tested.The coordinate distributions of phase and amplitude anisotropy of bile films and synovial fuid taken from the knee joint are determined and statistically analyzed.Criteria(statistical moments of 3rd and 4th orders)of differential diagnostics of early stages of cholelithiasis and septic arthritis of the knee joint with excellent balanced accuracy were determined.Data on the diagnostic fficiency of the Jones matrix tomography method for polyerystalline plasma(liver disease),urine(albuminuria)and cytological smears(cervical cancer)are presented.
文摘Super-continuum (SC) generated from optical fibers has many attractive applications in optical communication systems. Discussing the mechanism of wideband and flat SC generation, we describe all-optical signal processing that employs the SC.
基金Project supported by the National Natural Science Foundation of China(Grant No.61300203)
文摘It is striking that the quantum Zeno effect can be used to launch a direct counterfactual communication between two spatially separated parties, Alice and Bob. So far, existing protocols of this type only provide a deterministic counterfactual communication service. However, this counterfactuality should be payed at a price. Firstly, the transmission time is much longer than a classical transmission costs. Secondly, the chained-cycle structure makes them more sensitive to channel noises. Here, we extend the idea of counterfactual communication, and present a probabilistic-counterfactual quantum communication protocol, which is proved to have advantages over the deterministic ones. Moreover, the presented protocol could evolve to a deterministic one solely by adjusting the parameters of the beam splitters.