We demonstrate a triple-pass scheme for coherent transfer of optical frequency and the delay effect on the fiber phase noise compensation. It is theoretically proved that the delay effect consists of both fiber delay ...We demonstrate a triple-pass scheme for coherent transfer of optical frequency and the delay effect on the fiber phase noise compensation. It is theoretically proved that the delay effect consists of both fiber delay and servo delay. The delay effect confines the servo bandwidth within 1/8 and induces a residual fiber phase noise after noise compensation. For a 25-km-long fiber, the servo bandwidth is found to be around 1 k Hz, and the fiber phase noise is suppressed approaching to the theoretical limitation. The triple-pass scheme enables the simultaneous transfer of optical frequency to multiple remote users. The performance of noise compensator in the triple-pass scheme can achieve a similar level result compared with that in the double-pass scheme.展开更多
Optical transfer delay(OTD)is essential for distributed coherent systems,optically controlled phased arrays,fiber sensing systems,and quantum communication systems.However,existing OTD measurement techniques typically...Optical transfer delay(OTD)is essential for distributed coherent systems,optically controlled phased arrays,fiber sensing systems,and quantum communication systems.However,existing OTD measurement techniques typically involve trade-offs among accuracy,range,and speed,limiting the application in the fields.Herein,we propose a single-shot OTD measurement approach that simultaneously achieves high-accuracy,long-range,and high-speed measurement.A microwave photonic phase-derived ranging with a nonlinear interval microwave frequency comb(MFC)and a discrete frequency sampling technique is proposed to conserve both frequency and time resources,ensuring high-accuracy and ambiguity-free measurements.In the proof-of-concept experiment,a delay measurement uncertainty at the 10^(-9) level with a single 10μs sampling time is first reported,to our knowledge.The method is also applied to coherently combine two distributed signals at 31.8 GHz,separated by a 2 km optical fiber.A minimal gain loss of less than 0.0038 d B compared to the theoretical value was achieved,corresponding to an OTD synchronization accuracy of 0.3 ps.展开更多
High accuracy and time resolution optical transfer delay(OTD)measurement is highly desired in many multi-path applications,such as optical true-time-delay-based array systems and distributed optical sensors.However,th...High accuracy and time resolution optical transfer delay(OTD)measurement is highly desired in many multi-path applications,such as optical true-time-delay-based array systems and distributed optical sensors.However,the time resolution is usually limited by the frequency range of the probe signal in frequency-multiplexed OTD measurement techniques.Here,we proposed a time-resolution enhanced OTD measurement method based on incoherent optical frequency domain reflectometry(I-OFDR),where an adaptive filter is designed to suppress the spectral leakage from other paths to break the resolution limitation.A weighted least square(WLS)cost function is first established,and then an iteration approach is used to minimize the cost function.Finally,the appropriate filter parameter is obtained according to the convergence results.In a proof-of-concept experiment,the time-domain response of two optical links with a length difference of 900 ps is successfully estimated by applying a probe signal with a bandwidth of 400 MHz.The time resolution is improved by 2.78times compared to the theoretical resolution limit of the inverse discrete Fourier transform(iDFT)algorithm.In addition,the OTD measurement error is below±0.8 ps.The proposed algorithm provides a novel way to improve the measurement resolution without applying a probe signal with a large bandwidth,avoiding measurement errors induced by the dispersion effect.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No 61378037the Fundamental Research Funds for the Central Universities under Grant No JUSRP51628B
文摘We demonstrate a triple-pass scheme for coherent transfer of optical frequency and the delay effect on the fiber phase noise compensation. It is theoretically proved that the delay effect consists of both fiber delay and servo delay. The delay effect confines the servo bandwidth within 1/8 and induces a residual fiber phase noise after noise compensation. For a 25-km-long fiber, the servo bandwidth is found to be around 1 k Hz, and the fiber phase noise is suppressed approaching to the theoretical limitation. The triple-pass scheme enables the simultaneous transfer of optical frequency to multiple remote users. The performance of noise compensator in the triple-pass scheme can achieve a similar level result compared with that in the double-pass scheme.
基金National Natural Science Foundation of China(62271249,62075095)Fundamental Research Funds for the Central UniversitiesFunding for Outstanding Doctoral Dissertation in NUAA(BCXJ24-09)。
文摘Optical transfer delay(OTD)is essential for distributed coherent systems,optically controlled phased arrays,fiber sensing systems,and quantum communication systems.However,existing OTD measurement techniques typically involve trade-offs among accuracy,range,and speed,limiting the application in the fields.Herein,we propose a single-shot OTD measurement approach that simultaneously achieves high-accuracy,long-range,and high-speed measurement.A microwave photonic phase-derived ranging with a nonlinear interval microwave frequency comb(MFC)and a discrete frequency sampling technique is proposed to conserve both frequency and time resources,ensuring high-accuracy and ambiguity-free measurements.In the proof-of-concept experiment,a delay measurement uncertainty at the 10^(-9) level with a single 10μs sampling time is first reported,to our knowledge.The method is also applied to coherently combine two distributed signals at 31.8 GHz,separated by a 2 km optical fiber.A minimal gain loss of less than 0.0038 d B compared to the theoretical value was achieved,corresponding to an OTD synchronization accuracy of 0.3 ps.
基金supported by the National Natural Science Foundation of China(Nos.62075095 and 62271249)the Key Research and Development Program of Jiangsu Province(No.BE2020030)。
文摘High accuracy and time resolution optical transfer delay(OTD)measurement is highly desired in many multi-path applications,such as optical true-time-delay-based array systems and distributed optical sensors.However,the time resolution is usually limited by the frequency range of the probe signal in frequency-multiplexed OTD measurement techniques.Here,we proposed a time-resolution enhanced OTD measurement method based on incoherent optical frequency domain reflectometry(I-OFDR),where an adaptive filter is designed to suppress the spectral leakage from other paths to break the resolution limitation.A weighted least square(WLS)cost function is first established,and then an iteration approach is used to minimize the cost function.Finally,the appropriate filter parameter is obtained according to the convergence results.In a proof-of-concept experiment,the time-domain response of two optical links with a length difference of 900 ps is successfully estimated by applying a probe signal with a bandwidth of 400 MHz.The time resolution is improved by 2.78times compared to the theoretical resolution limit of the inverse discrete Fourier transform(iDFT)algorithm.In addition,the OTD measurement error is below±0.8 ps.The proposed algorithm provides a novel way to improve the measurement resolution without applying a probe signal with a large bandwidth,avoiding measurement errors induced by the dispersion effect.
