A scheme for instantaneous frequency measurement(IFM)using two parallel I/Q modulators based on optical power monitoring is proposed.The amplitude comparison function(ACF)can be constructed to establish the relationsh...A scheme for instantaneous frequency measurement(IFM)using two parallel I/Q modulators based on optical power monitoring is proposed.The amplitude comparison function(ACF)can be constructed to establish the relationship between the frequency of radio frequency(RF)signal and the power ratio of two optical signals output by two I/Q modulators.The frequency of RF signal can be derived by measuring the optical power of the optical signals output by two I/Q modulators.The measurement range and measurement error can be adjusted by controlling the delay amount of the electrical delay line.The feasibility of the scheme is verified,and the corresponding measurement range and measurement error of the system under different delay amounts of the electrical delay line are given.Compared with previous IFM schemes,the structure of this scheme is simple.Polarization devices,a photodetector and an electrical power meter are not used,which reduces the impact of the environmental disturbance on the system and the cost of the system.In simulation,the measurement range can reach 0 GHz-24.5 GHz by adjusting the delay amount of the electrical delay lineτ=20 ps.The measurement error of the scheme is better at low frequency,and the measurement error of low frequency 0 GHz-9.6 GHz can reach-0.1 GHz to+0.05 GHz.展开更多
High-performance interrogation systems for optical fiber sensors are extensively required for environmental condition monitoring applications.In this article,we propose and demonstrate a Michelson interferometer(MI)in...High-performance interrogation systems for optical fiber sensors are extensively required for environmental condition monitoring applications.In this article,we propose and demonstrate a Michelson interferometer(MI)interrogation system based on an optoelectronic oscillator(OEO).The frequency of the OEO is related to the free spectral range(FSR)of the MI.Thus,when the FSR of the MI varies with a change in external physical factors,the frequency of the OEO shifts and can be used for interrogation.We demonstrate that the temperature sensitivity and interrogation resolution are 35.35 MHz/℃and 0.012℃,respectively.Such an OEO-based scheme enables wavelength-to-frequency mapping and promises a wide linear interrogation range,high resolution and high-speed interrogation.展开更多
The photonic neural processing unit(PNPU)demonstrates ultrahigh inference speed with low energy consumption,and it has become a promising hardware artificial intelligence(AI)accelerator.However,the nonidealities of th...The photonic neural processing unit(PNPU)demonstrates ultrahigh inference speed with low energy consumption,and it has become a promising hardware artificial intelligence(AI)accelerator.However,the nonidealities of the photonic device and the peripheral circuit make the practical application much more complex.Rather than optimizing the photonic device,the architecture,and the algorithm individually,a joint device-architecture-algorithm codesign method is proposed to improve the accuracy,efficiency and robustness of the PNPU.First,a full-flow simulator for the PNPU is developed from the back end simulator to the high-level training framework;Second,the full system architecture and the complete photonic chip design enable the simulator to closely model the real system;Third,the nonidealities of the photonic chip are evaluated for the PNPU design.The average test accuracy exceeds 98%,and the computing power exceeds 100TOPS.展开更多
We propose and analyze a silicon hybrid plasmonic polarization splitter-rotator with an ultra-short footprint using an asymmetric bent directional coupler on a silicon-on-insulator platform.Benefitting from the large ...We propose and analyze a silicon hybrid plasmonic polarization splitter-rotator with an ultra-short footprint using an asymmetric bent directional coupler on a silicon-on-insulator platform.Benefitting from the large birefringence induced by the bent structure and plasmonic effect,the cross-polarization coupling length is only 5.21μm.The transverse magnetic to transverse electric polarization conversion efficiency is over 99.9%,with an extinction ratio of 20.6 dB(32.5 dB)for the transverse magnetic(transverse electric)mode at 1.55μm.Furthermore,the polarization conversion efficiency is higher than 90%while maintaining cross talk below-19 dB within the bandwidth of 80 nm.展开更多
A high sensitivity D-shaped hole double-cladding fiber temperature sensor based on surface plasmon resonance(SPR)is designed and investigated by a full-vector finite element method.Within the D-shaped hole doublecladd...A high sensitivity D-shaped hole double-cladding fiber temperature sensor based on surface plasmon resonance(SPR)is designed and investigated by a full-vector finite element method.Within the D-shaped hole doublecladding fiber,the hollow D-section is coated with gold film and then injected in a high thermo-optic coefficient liquid to realize the high temperature sensitivity for the fiber SPR temperature sensor.The numerical simulation results show that the peaking loss of the D-shaped hole double-cladding fiber SPR is hugely influenced by the distance between the D-shaped hole and fiber core and by the thickness of the gold film,but the temperature sensitivity is almost insensitive to the above parameters.When the thermo-optic coefficient is -2.8×10^(-4)∕℃,the thickness of the gold film is 47 nm,and the distance between the D-shaped hole and fiber core is 5μm,the temperature sensitivity of the D-shaped hole fiber SPR sensor can reach to -3.635 nm∕℃.展开更多
A refractive index intensity detecting sensor with long-period grating written in the single-mode–thin-core–single-mode fiber(STS) structure is proposed and optimized theoretically.The sensor is composed of two sing...A refractive index intensity detecting sensor with long-period grating written in the single-mode–thin-core–single-mode fiber(STS) structure is proposed and optimized theoretically.The sensor is composed of two single-mode fibers connected by a section of long-period fiber grating fabricated on thin-core fiber.After optimization and benefitting from the phase matching point, the loss peak of the structure can reach 62.8dB theoretically.The wavelength of the characteristic peak is fixed at the phase matching point, so intensity detection can be achieved.The sensitivity can reach 272.5dB/RIU.The structural optimization in this Letter provides a reference for the fabrication of an easy-made all-fiber sensor without extra cladding.展开更多
This paper firstly and experimentally demonstrates an in-fiber axial micro-strain sensing head,combined with a Mach-Zehnder interferometer(MZI)based on the concentric multilayer elliptical-core fiber(CMECF).This MZI w...This paper firstly and experimentally demonstrates an in-fiber axial micro-strain sensing head,combined with a Mach-Zehnder interferometer(MZI)based on the concentric multilayer elliptical-core fiber(CMECF).This MZI with a high extinction ratio(about 15dB)is successfully achieved with a CMECF-single mode fiber-CMECF(CSC)structure.The MZI sensor theory and the resonance demodulation technology are systematically described in this paper.In this CSC structure, two sections of the CMECF have a role as the mode generator and coupler,respectively.LP01 and LPlleven,which have similar excitation coefficients,are two dominated propagating mode groups supported in the CMECF.On account of the distinct dual-mode property,a good stability of this sensor is realized.The detected resonance in the MZI shifts as the axial micro-strain variated due to the strong interaction between higher order modes.High sensitivity of^1.78pm/με is experimentally achieved within the range of 0με-1250με,meanwhile,the intensity fluctuation is below 0.38dB.展开更多
A kind of tapered segmented cladding fiber(T-SCF)with large mode area(LMA)is proposed,and the mode and amplification characteristics of T-SCFs with concave,linear,and convex tapered structures are investigated based o...A kind of tapered segmented cladding fiber(T-SCF)with large mode area(LMA)is proposed,and the mode and amplification characteristics of T-SCFs with concave,linear,and convex tapered structures are investigated based on finite-element method(FEM)and few-mode steady-state rate equation.Simulation results indicate that the concave tapered structure can introduce high loss for high-order modes(HOMs)that is advantageous to achieve single-mode operation,whereas the convex tapered structure provides large effective mode area that can help to mitigate nonlinear effects.Meanwhile,the small-to-large amplification scheme shows further advantages on stripping off HOMs,and the large-to-small amplification scheme decreases the heat load density induced by the high-power pump.Moreover,singlemode propagation performance,effective mode area,and heat load density of the T-SCF are superior to those of tapered step index fiber(T-SIF).These theoretical model and numerical results can provide instructive suggestions for designing high-power fiber lasers and amplifiers.展开更多
A tunable multi-wavelength erbium-doped fiber laser with precise wavelength interval control is reported theoretically and experimentally in this paper.It is made up of a Mach-Zehnder interferometer [MZI] filter and a...A tunable multi-wavelength erbium-doped fiber laser with precise wavelength interval control is reported theoretically and experimentally in this paper.It is made up of a Mach-Zehnder interferometer [MZI] filter and a Sagnac filter and supplemerited by the four-wave-mixing effect.Compared with other filters,the proposed MZI filter based on the fused taper technology can change the wavelength interval more flexibly.The experiment result shows that wavelength tuning can be achieved,and the tuning range can reach-15 nm.Moreover,the variation in the number of wavelengths is also realized.The maximum side-mode suppression ratio can reach 39 dB.展开更多
An approach for full duty frequency-doubled triangle shape lightwave generation is proposed and demonstrated.It requires a dual-parallel Mach–Zehnder modulator（DP-MZM） driven by a sinusoidal signal. A stop band fil...An approach for full duty frequency-doubled triangle shape lightwave generation is proposed and demonstrated.It requires a dual-parallel Mach–Zehnder modulator（DP-MZM） driven by a sinusoidal signal. A stop band filter is coupled to filter out two undesired sidebands. By tuning the bias voltage applied to the DP-MZM, the output optical intensity with a full duty cycle triangle shape profile can be obtained. It is found that the required modulation index is no longer a fixed one. It can vary within a range, without degrading the target waveform. The principle is analyzed by theory and evaluated by simulation. A proof-of-concept experiment is also conducted.Good agreements between theoretical prediction and experimental results have been found. This approach might be attractive due to the feature of a variable modulation index, which insures simple operation in practice.展开更多
基金the National Key Research and Development Program of China(Grant No.2018YFB1801003)the National Natural Science Foundation of China(Grant Nos.61525501 and 61827817)the Beijing Natural Science Foundation,China(Grant No.4192022).
文摘A scheme for instantaneous frequency measurement(IFM)using two parallel I/Q modulators based on optical power monitoring is proposed.The amplitude comparison function(ACF)can be constructed to establish the relationship between the frequency of radio frequency(RF)signal and the power ratio of two optical signals output by two I/Q modulators.The frequency of RF signal can be derived by measuring the optical power of the optical signals output by two I/Q modulators.The measurement range and measurement error can be adjusted by controlling the delay amount of the electrical delay line.The feasibility of the scheme is verified,and the corresponding measurement range and measurement error of the system under different delay amounts of the electrical delay line are given.Compared with previous IFM schemes,the structure of this scheme is simple.Polarization devices,a photodetector and an electrical power meter are not used,which reduces the impact of the environmental disturbance on the system and the cost of the system.In simulation,the measurement range can reach 0 GHz-24.5 GHz by adjusting the delay amount of the electrical delay lineτ=20 ps.The measurement error of the scheme is better at low frequency,and the measurement error of low frequency 0 GHz-9.6 GHz can reach-0.1 GHz to+0.05 GHz.
文摘High-performance interrogation systems for optical fiber sensors are extensively required for environmental condition monitoring applications.In this article,we propose and demonstrate a Michelson interferometer(MI)interrogation system based on an optoelectronic oscillator(OEO).The frequency of the OEO is related to the free spectral range(FSR)of the MI.Thus,when the FSR of the MI varies with a change in external physical factors,the frequency of the OEO shifts and can be used for interrogation.We demonstrate that the temperature sensitivity and interrogation resolution are 35.35 MHz/℃and 0.012℃,respectively.Such an OEO-based scheme enables wavelength-to-frequency mapping and promises a wide linear interrogation range,high resolution and high-speed interrogation.
基金supported by the National Natural Science Foundation of China(Grant No.61827817)。
文摘The photonic neural processing unit(PNPU)demonstrates ultrahigh inference speed with low energy consumption,and it has become a promising hardware artificial intelligence(AI)accelerator.However,the nonidealities of the photonic device and the peripheral circuit make the practical application much more complex.Rather than optimizing the photonic device,the architecture,and the algorithm individually,a joint device-architecture-algorithm codesign method is proposed to improve the accuracy,efficiency and robustness of the PNPU.First,a full-flow simulator for the PNPU is developed from the back end simulator to the high-level training framework;Second,the full system architecture and the complete photonic chip design enable the simulator to closely model the real system;Third,the nonidealities of the photonic chip are evaluated for the PNPU design.The average test accuracy exceeds 98%,and the computing power exceeds 100TOPS.
基金partially supported by the National Natural Science Foundation of China(NSFC)(Nos.61827817 and 61525501)。
文摘We propose and analyze a silicon hybrid plasmonic polarization splitter-rotator with an ultra-short footprint using an asymmetric bent directional coupler on a silicon-on-insulator platform.Benefitting from the large birefringence induced by the bent structure and plasmonic effect,the cross-polarization coupling length is only 5.21μm.The transverse magnetic to transverse electric polarization conversion efficiency is over 99.9%,with an extinction ratio of 20.6 dB(32.5 dB)for the transverse magnetic(transverse electric)mode at 1.55μm.Furthermore,the polarization conversion efficiency is higher than 90%while maintaining cross talk below-19 dB within the bandwidth of 80 nm.
基金National Natural Science Foundation of China(NSFC)(61525501)
文摘A high sensitivity D-shaped hole double-cladding fiber temperature sensor based on surface plasmon resonance(SPR)is designed and investigated by a full-vector finite element method.Within the D-shaped hole doublecladding fiber,the hollow D-section is coated with gold film and then injected in a high thermo-optic coefficient liquid to realize the high temperature sensitivity for the fiber SPR temperature sensor.The numerical simulation results show that the peaking loss of the D-shaped hole double-cladding fiber SPR is hugely influenced by the distance between the D-shaped hole and fiber core and by the thickness of the gold film,but the temperature sensitivity is almost insensitive to the above parameters.When the thermo-optic coefficient is -2.8×10^(-4)∕℃,the thickness of the gold film is 47 nm,and the distance between the D-shaped hole and fiber core is 5μm,the temperature sensitivity of the D-shaped hole fiber SPR sensor can reach to -3.635 nm∕℃.
基金supported by the National Natural Science Foundation of China (Nos. 61827817 and 61525501)
文摘A refractive index intensity detecting sensor with long-period grating written in the single-mode–thin-core–single-mode fiber(STS) structure is proposed and optimized theoretically.The sensor is composed of two single-mode fibers connected by a section of long-period fiber grating fabricated on thin-core fiber.After optimization and benefitting from the phase matching point, the loss peak of the structure can reach 62.8dB theoretically.The wavelength of the characteristic peak is fixed at the phase matching point, so intensity detection can be achieved.The sensitivity can reach 272.5dB/RIU.The structural optimization in this Letter provides a reference for the fabrication of an easy-made all-fiber sensor without extra cladding.
文摘This paper firstly and experimentally demonstrates an in-fiber axial micro-strain sensing head,combined with a Mach-Zehnder interferometer(MZI)based on the concentric multilayer elliptical-core fiber(CMECF).This MZI with a high extinction ratio(about 15dB)is successfully achieved with a CMECF-single mode fiber-CMECF(CSC)structure.The MZI sensor theory and the resonance demodulation technology are systematically described in this paper.In this CSC structure, two sections of the CMECF have a role as the mode generator and coupler,respectively.LP01 and LPlleven,which have similar excitation coefficients,are two dominated propagating mode groups supported in the CMECF.On account of the distinct dual-mode property,a good stability of this sensor is realized.The detected resonance in the MZI shifts as the axial micro-strain variated due to the strong interaction between higher order modes.High sensitivity of^1.78pm/με is experimentally achieved within the range of 0με-1250με,meanwhile,the intensity fluctuation is below 0.38dB.
基金the National Key R&D Program of China(No.2020YFB1805802)National Natural Science Foundation of China(Nos.62005012 and 61827817)+1 种基金State Key Laboratory of Rail Traffic Control and Safety(No.RCS2019ZZ007)Beijing Jiaotong University,and Shandong Province Higher Educational Science and Technology Program(No.J18KA368).
文摘A kind of tapered segmented cladding fiber(T-SCF)with large mode area(LMA)is proposed,and the mode and amplification characteristics of T-SCFs with concave,linear,and convex tapered structures are investigated based on finite-element method(FEM)and few-mode steady-state rate equation.Simulation results indicate that the concave tapered structure can introduce high loss for high-order modes(HOMs)that is advantageous to achieve single-mode operation,whereas the convex tapered structure provides large effective mode area that can help to mitigate nonlinear effects.Meanwhile,the small-to-large amplification scheme shows further advantages on stripping off HOMs,and the large-to-small amplification scheme decreases the heat load density induced by the high-power pump.Moreover,singlemode propagation performance,effective mode area,and heat load density of the T-SCF are superior to those of tapered step index fiber(T-SIF).These theoretical model and numerical results can provide instructive suggestions for designing high-power fiber lasers and amplifiers.
基金supported by the National Key R&D Program of China (No. 2018YFB1801003)in part by the National Natural Science Foundation of China (No. 61827817)
文摘A tunable multi-wavelength erbium-doped fiber laser with precise wavelength interval control is reported theoretically and experimentally in this paper.It is made up of a Mach-Zehnder interferometer [MZI] filter and a Sagnac filter and supplemerited by the four-wave-mixing effect.Compared with other filters,the proposed MZI filter based on the fused taper technology can change the wavelength interval more flexibly.The experiment result shows that wavelength tuning can be achieved,and the tuning range can reach-15 nm.Moreover,the variation in the number of wavelengths is also realized.The maximum side-mode suppression ratio can reach 39 dB.
基金supported in part by the National Natural Science Foundation of China under Grant No.61405007
文摘An approach for full duty frequency-doubled triangle shape lightwave generation is proposed and demonstrated.It requires a dual-parallel Mach–Zehnder modulator（DP-MZM） driven by a sinusoidal signal. A stop band filter is coupled to filter out two undesired sidebands. By tuning the bias voltage applied to the DP-MZM, the output optical intensity with a full duty cycle triangle shape profile can be obtained. It is found that the required modulation index is no longer a fixed one. It can vary within a range, without degrading the target waveform. The principle is analyzed by theory and evaluated by simulation. A proof-of-concept experiment is also conducted.Good agreements between theoretical prediction and experimental results have been found. This approach might be attractive due to the feature of a variable modulation index, which insures simple operation in practice.
