电力设备局部放电易引发电气短路故障,传统的电检测方法针对单点测量,在长距离测量上受到局限。分析了局部放电的参数特征,设计了一种检测局部放电信号的光纤环结构,并构建了基于Sagnac干涉原理的光纤传感局部放电检测方案。在实验室环...电力设备局部放电易引发电气短路故障,传统的电检测方法针对单点测量,在长距离测量上受到局限。分析了局部放电的参数特征,设计了一种检测局部放电信号的光纤环结构,并构建了基于Sagnac干涉原理的光纤传感局部放电检测方案。在实验室环境下模拟电力设备局部放电,搭建了局部放电光纤检测系统,传感光纤总长度为8.398 km,进行局部放电检测试验。试验证明,在10 k V电压等级下,局部放电时域信号幅值范围为0.1 V^1.8 V,频率响应范围为可达60 k Hz,研究表明该方法具有灵敏度高、频率响应范围宽等特点,为电力设备局部放电检测提供了新的思路。展开更多
A high-sensitivity all-fiber temperature sensor based on a Sagnac interferometer is demonstrated by splicing a section of polarization maintaining fiber(PMF)between two sections of standard single mode fibers(SMFs).In...A high-sensitivity all-fiber temperature sensor based on a Sagnac interferometer is demonstrated by splicing a section of polarization maintaining fiber(PMF)between two sections of standard single mode fibers(SMFs).In this sensor,the SMF-PMF-SMF structure in the Sagnac loop is bent into a circle to enhance the sensitivity.The length and curvature of the PMF in the loop are investigated and can be optimized to further increase the temperature sensitivity of the sensor. Results show that the radius of the circle has an important effect upon temperature sensitivity due to the bend-induced birefringence variation of the PMF.The SMF-PMF-SMF structure bent into a circle with a radius of 30mm exhibits a high-sensitivity temperature of 1.73nm/℃.The sensor is provided with the advantages of easy fabrication,low-insertion loss,and high sensitivity,which may find potential applications in the field of high precision temperature measurement.展开更多
The coexistence of a noise-like pulse(NLP)and a dark pulse was experimentally demonstrated in a net-anomalous dispersion Er/Yb co-doped fiber(EYDF)laser,for the first time,to our knowledge.The cavity was mode-locked b...The coexistence of a noise-like pulse(NLP)and a dark pulse was experimentally demonstrated in a net-anomalous dispersion Er/Yb co-doped fiber(EYDF)laser,for the first time,to our knowledge.The cavity was mode-locked by nonlinear polarization rotation(NPR)technique.Meanwhile,a Sagnac loop with a section of polarization-maintaining fiber(PMF)was used as a comb filter to enable multiwavelength pulse operation.When the PMF length was 0.3 m,an asymmetric two-peak spectrum with central wavelengths of 1565.3 and 1594.2 nm was obtained by adjusting polarization controllers(PCs).It is a composite state of NLP and dark pulse due to the cross-phase modulation between the two different wavelength components along orthogonal polarization axes.The two pulses are synchronized with a repetition rate of 7.53 MHz.By adjusting the PC in the Sagnac loop,the spectral ranges of NLPs and dark pulses can be tuned from 1560 to 1577.8 nm and from 1581.8 to 1605.4 nm,respectively.In addition,the pulse characteristics were investigated by incorporating the PMF with different lengths,where the coexistence patterns can be generated when the PMF lengths were 0.2 and 0.3 m.A longer PMF can lead to a narrowband comb filtering,which causes a larger loss and is not favorable for stable operation of the coexistence regime.This fiber laser demonstrates an interesting operation regime and has significant potential for numerous practical applications.展开更多
Hyperentanglement, the simultaneous entanglement in more than one degree of freedom(DOF), plays an important role in quantum communication and quantum information processing for it can effectively increase the channel...Hyperentanglement, the simultaneous entanglement in more than one degree of freedom(DOF), plays an important role in quantum communication and quantum information processing for it can effectively increase the channel capacity. Existing hyperentanglement sources mainly focus on the generation of the hyperentanglement in two DOFs. In this paper, we design the generation protocols for three kinds of hyperentanglement encoded in three DOFs with the practical coherent pulses sources, including the polarization-frequency-space hyperentanglement, the polarization-frequency-time-bin hyperentanglement, and the polarizationspace-time-bin hyperentanglement. These protocols exploit the spontaneous parametric down-conversion(SPDC) process and the Sagnac interferometer. The three protocols are all based on feasible experimental condition and may have potential applications in future hyperentanglement-based quantum communication and quantum information processing protocols.展开更多
A distributed optical fiber disturbance detection system consisted of a Sagnac interferometer and a Mach-Zehnder interferometer is demonstrated. Two interferometers outputs are connected to an electric band-pass filte...A distributed optical fiber disturbance detection system consisted of a Sagnac interferometer and a Mach-Zehnder interferometer is demonstrated. Two interferometers outputs are connected to an electric band-pass filter via a detector respectively. The central frequencies of the two filters are selected adaptively according to the disturbance frequency. The disturbance frequency is obtained by either frequency spectrum of the two interferometers outputs. An alarm is given out only when the Sagnac interferometer output is changed. A disturbance position is determined by calculating a time difference with a cross-correlation method between the filter output connected to the Sagnac interferometer and derivative of the filter output connected to the Mach-Zehnder interferometer. The frequency spectrum, derivative and cross-correlation are obtained by a signal processing system. Theory analysis and simulation results are presented. They show that the system structure and location method are effective, accurate, and immune to environmental variations.展开更多
By combining a silicon-based lithium niobate modulator and a silicon-based Si3N4resonator with silicon-based photonics technology,a highly systematic design of a hybrid integrated optical gyroscope with enhanced recip...By combining a silicon-based lithium niobate modulator and a silicon-based Si3N4resonator with silicon-based photonics technology,a highly systematic design of a hybrid integrated optical gyroscope with enhanced reciprocity sensitivity and a dual micro-ring structure is proposed for the first time in this paper.The relationship between the device's structural parameters and optical performance is also analyzed by constructing a complete simulation link,which provides a theoretical design reference to improve the system's sensitivity.When the wavelength is 1550 nm,the conversion frequency of the dual-ring optical path is 50 MHz,the coupling coefficient is 0.2,and the radius R is 1000μm,the quality factor of the silicon-based Si_(3)N_(4)resonator is 2.58×10^(5),which is 1.58 times that of the silicon-on-insulator resonator.Moreover,the effective number of times the light travels around the ring before leaving the micro-ring is 5.93,which is 1.62 times that of the silicon-on-insulator resonator.The work fits the gyro dynamic output diagram,and solves the problem of low sensitivity at low speed by setting the phase offset.This results provide a basis for the further optimization of design and chip processing of the integrated optical gyroscope.展开更多
A high-sensitivity temperature sensor based on the harmonic Vernier effect is proposed and verified by experiments.The main component of the sensor is a Sagnac interferometer consisting of two sections of polarization...A high-sensitivity temperature sensor based on the harmonic Vernier effect is proposed and verified by experiments.The main component of the sensor is a Sagnac interferometer consisting of two sections of polarization maintaining fibers(PMFs)spliced with an intersection angle of 45o between their fast axes.The harmonic Vernier effect is achieved by setting the length of one of the PMFs an integral multiple(i-times)of the length of the other plus a detuning factor.Compared with the Sagnac interferometer based on the fundamental Vernier effect,the temperature sensitivity of the harmonic Vernier effect is higher,reaching i+1 times of that of the fundamental Vernier effect(i is the order of the harmonic).展开更多
Combining a Ti-diffusion periodically poled lithium niobate(PPLN)waveguide with a Sagnac interferometer,two opposite directions type-II spontaneous parametric down conversions(SPDC)occur coherently and yield a high br...Combining a Ti-diffusion periodically poled lithium niobate(PPLN)waveguide with a Sagnac interferometer,two opposite directions type-II spontaneous parametric down conversions(SPDC)occur coherently and yield a high brightness,high stability polarization entanglement source.The source produces degenerate photon pairs at 1540.4 nm with a brightness of B=(1.36±0.03)×10^(6) pairs/(s·nm·m W).We perform quantum state tomography to reconstruct the density matrix of the output state and obtain a fidelity of F=0.983±0.001.The high brightness and phase stability of our waveguide source enable a wide range of quantum information experiments operating at a low pump power as well as hold the advantage in mass production which can promote the practical applications of quantum technologies.展开更多
文摘电力设备局部放电易引发电气短路故障,传统的电检测方法针对单点测量,在长距离测量上受到局限。分析了局部放电的参数特征,设计了一种检测局部放电信号的光纤环结构,并构建了基于Sagnac干涉原理的光纤传感局部放电检测方案。在实验室环境下模拟电力设备局部放电,搭建了局部放电光纤检测系统,传感光纤总长度为8.398 km,进行局部放电检测试验。试验证明,在10 k V电压等级下,局部放电时域信号幅值范围为0.1 V^1.8 V,频率响应范围为可达60 k Hz,研究表明该方法具有灵敏度高、频率响应范围宽等特点,为电力设备局部放电检测提供了新的思路。
基金the National Natural Science Foundation of China(NSFC)(Grant Nos.61425007 and 61635007)Guangdong Natural Science Foundation(Grant Nos.2015B010105007 and 2014A030308007)+3 种基金Science and Technology Innovation Commission of Shenzhen(Grant Nos.JCYJ20170412105604705 and JCYJ20160427104925452)Development and Reform Commission of Shenzhen Municipality Foundationthe National Natural Science Foundation of China(Grant No.61565002)Guangxi Province Key Research and Development Program(Grant No.AB171129027).
文摘A high-sensitivity all-fiber temperature sensor based on a Sagnac interferometer is demonstrated by splicing a section of polarization maintaining fiber(PMF)between two sections of standard single mode fibers(SMFs).In this sensor,the SMF-PMF-SMF structure in the Sagnac loop is bent into a circle to enhance the sensitivity.The length and curvature of the PMF in the loop are investigated and can be optimized to further increase the temperature sensitivity of the sensor. Results show that the radius of the circle has an important effect upon temperature sensitivity due to the bend-induced birefringence variation of the PMF.The SMF-PMF-SMF structure bent into a circle with a radius of 30mm exhibits a high-sensitivity temperature of 1.73nm/℃.The sensor is provided with the advantages of easy fabrication,low-insertion loss,and high sensitivity,which may find potential applications in the field of high precision temperature measurement.
基金This work was supported by the National Natural Science Foundation of China(NSFC)(No.61575018).
文摘The coexistence of a noise-like pulse(NLP)and a dark pulse was experimentally demonstrated in a net-anomalous dispersion Er/Yb co-doped fiber(EYDF)laser,for the first time,to our knowledge.The cavity was mode-locked by nonlinear polarization rotation(NPR)technique.Meanwhile,a Sagnac loop with a section of polarization-maintaining fiber(PMF)was used as a comb filter to enable multiwavelength pulse operation.When the PMF length was 0.3 m,an asymmetric two-peak spectrum with central wavelengths of 1565.3 and 1594.2 nm was obtained by adjusting polarization controllers(PCs).It is a composite state of NLP and dark pulse due to the cross-phase modulation between the two different wavelength components along orthogonal polarization axes.The two pulses are synchronized with a repetition rate of 7.53 MHz.By adjusting the PC in the Sagnac loop,the spectral ranges of NLPs and dark pulses can be tuned from 1560 to 1577.8 nm and from 1581.8 to 1605.4 nm,respectively.In addition,the pulse characteristics were investigated by incorporating the PMF with different lengths,where the coexistence patterns can be generated when the PMF lengths were 0.2 and 0.3 m.A longer PMF can lead to a narrowband comb filtering,which causes a larger loss and is not favorable for stable operation of the coexistence regime.This fiber laser demonstrates an interesting operation regime and has significant potential for numerous practical applications.
基金supported by the National Natural Science Foundation of China(Grant Nos.11974189,12175106,and 92365110)Postgraduate Research&Practice Innovation Program of Jiangsu Province(Grant No.KYCX23-1027)。
文摘Hyperentanglement, the simultaneous entanglement in more than one degree of freedom(DOF), plays an important role in quantum communication and quantum information processing for it can effectively increase the channel capacity. Existing hyperentanglement sources mainly focus on the generation of the hyperentanglement in two DOFs. In this paper, we design the generation protocols for three kinds of hyperentanglement encoded in three DOFs with the practical coherent pulses sources, including the polarization-frequency-space hyperentanglement, the polarization-frequency-time-bin hyperentanglement, and the polarizationspace-time-bin hyperentanglement. These protocols exploit the spontaneous parametric down-conversion(SPDC) process and the Sagnac interferometer. The three protocols are all based on feasible experimental condition and may have potential applications in future hyperentanglement-based quantum communication and quantum information processing protocols.
基金Project supported by the Innovation Program of Education Commission of Shanghai Municipality (Grant No.10YZ19)the Shanghai Leading Academic Discipline Project (Grant No.S30108)the Shanghai Key Laboratory of Specialty Fiber Optics and Optical Access Networks (Grant No.SKLSFO200903)
文摘A distributed optical fiber disturbance detection system consisted of a Sagnac interferometer and a Mach-Zehnder interferometer is demonstrated. Two interferometers outputs are connected to an electric band-pass filter via a detector respectively. The central frequencies of the two filters are selected adaptively according to the disturbance frequency. The disturbance frequency is obtained by either frequency spectrum of the two interferometers outputs. An alarm is given out only when the Sagnac interferometer output is changed. A disturbance position is determined by calculating a time difference with a cross-correlation method between the filter output connected to the Sagnac interferometer and derivative of the filter output connected to the Mach-Zehnder interferometer. The frequency spectrum, derivative and cross-correlation are obtained by a signal processing system. Theory analysis and simulation results are presented. They show that the system structure and location method are effective, accurate, and immune to environmental variations.
基金Project supported by the science and technology general project of Beijing Municipal Education Commission(Grant No.KM202111232019)Beijing Municipal Natural Science Foundation(Grant No.2214058)+4 种基金the Discipline Innovation Program of Higher Education(Grant No.D17021)the Open Project of the State Key Laboratory of Integrated Optoelectronics(Grant No.IOSKL2020KF22)Beijing Great Wall Scholars Program(Grant No.CIT&TCD20190323)the National Natural Science Foundation of China(Grant No.61875237)Beijing Youth Talent Support Program(Grant No.Z2019042)。
文摘By combining a silicon-based lithium niobate modulator and a silicon-based Si3N4resonator with silicon-based photonics technology,a highly systematic design of a hybrid integrated optical gyroscope with enhanced reciprocity sensitivity and a dual micro-ring structure is proposed for the first time in this paper.The relationship between the device's structural parameters and optical performance is also analyzed by constructing a complete simulation link,which provides a theoretical design reference to improve the system's sensitivity.When the wavelength is 1550 nm,the conversion frequency of the dual-ring optical path is 50 MHz,the coupling coefficient is 0.2,and the radius R is 1000μm,the quality factor of the silicon-based Si_(3)N_(4)resonator is 2.58×10^(5),which is 1.58 times that of the silicon-on-insulator resonator.Moreover,the effective number of times the light travels around the ring before leaving the micro-ring is 5.93,which is 1.62 times that of the silicon-on-insulator resonator.The work fits the gyro dynamic output diagram,and solves the problem of low sensitivity at low speed by setting the phase offset.This results provide a basis for the further optimization of design and chip processing of the integrated optical gyroscope.
基金supports from the National Natural Science Foundation of China(Grant No.62175116)1311 Talent Plan of Nanjing University of Posts and Telecommunications.
文摘A high-sensitivity temperature sensor based on the harmonic Vernier effect is proposed and verified by experiments.The main component of the sensor is a Sagnac interferometer consisting of two sections of polarization maintaining fibers(PMFs)spliced with an intersection angle of 45o between their fast axes.The harmonic Vernier effect is achieved by setting the length of one of the PMFs an integral multiple(i-times)of the length of the other plus a detuning factor.Compared with the Sagnac interferometer based on the fundamental Vernier effect,the temperature sensitivity of the harmonic Vernier effect is higher,reaching i+1 times of that of the fundamental Vernier effect(i is the order of the harmonic).
基金Project supported by the National Key R&D Program of China(Grant Nos.2022YFF0712800 and 2019YFA0308700)。
文摘Combining a Ti-diffusion periodically poled lithium niobate(PPLN)waveguide with a Sagnac interferometer,two opposite directions type-II spontaneous parametric down conversions(SPDC)occur coherently and yield a high brightness,high stability polarization entanglement source.The source produces degenerate photon pairs at 1540.4 nm with a brightness of B=(1.36±0.03)×10^(6) pairs/(s·nm·m W).We perform quantum state tomography to reconstruct the density matrix of the output state and obtain a fidelity of F=0.983±0.001.The high brightness and phase stability of our waveguide source enable a wide range of quantum information experiments operating at a low pump power as well as hold the advantage in mass production which can promote the practical applications of quantum technologies.
