A novel nonlinear mirror structure which can increase the optical signal-to-noise ratio of a distributed fiber Raman temperature sensor is proposed, and 6 dB improvement of the optical signal-to-noise ratio is obtaine...A novel nonlinear mirror structure which can increase the optical signal-to-noise ratio of a distributed fiber Raman temperature sensor is proposed, and 6 dB improvement of the optical signal-to-noise ratio is obtained. With the assistance of the nonlinear mirror, we demonstrate that the spatial resolution of the sensor is improved from 3 m to 1 m, and the temperature accuracy is improved from ±0.6℃ to ±0.2℃. The theoretical analysis and the experimental data are in good agreement.展开更多
Optical fibre sensors based on Brillouin scattering have been vigorously studied in the context of structural health monitoring on account of their capacity for distributed strain and temperature measurements.However,...Optical fibre sensors based on Brillouin scattering have been vigorously studied in the context of structural health monitoring on account of their capacity for distributed strain and temperature measurements.However,real-time distributed strain measurement has been achieved only for two-end-access systems;such systems reduce the degree of freedom in embedding the sensors into structures,and furthermore render the measurement no longer feasible when extremely high loss or breakage occurs at a point along the sensing fibre.Here,we demonstrate real-time distributed measurement with an intrinsically one-end-access reflectometry configuration by using a correlation-domain technique.In this method,the Brillouin gain spectrum is obtained at high speed using a voltage-controlled oscillator,and the Brillouin frequency shift is converted into a phase delay of a synchronous sinusoidal waveform;the phase delay is subsequently converted into a voltage,which can be directly measured.When a single-point measurement is performed at an arbitrary position,a strain sampling rate of up to 100 kHz is experimentally verified by detecting locally applied dynamic strain at 1 kHz.When distributed measurements are performed at 100 points with 10 times averaging,a repetition rate of 100 Hz is verified by tracking a mechanical wave propagating along the fibre.Some drawbacks of this ultrahigh-speed configuration,including the reduced measurement accuracy,lowered spatial resolution and limited strain dynamic range,are also discussed.展开更多
基金supported by the National Natural Science Foundation of China under Grant No.60377021partially supported by Program for New Century Excellent Talents in University under Grant No. NCET-07-0152Sichuan Scientific Funds for Young Researchers under Grant No. 08ZQ026-012.
文摘A novel nonlinear mirror structure which can increase the optical signal-to-noise ratio of a distributed fiber Raman temperature sensor is proposed, and 6 dB improvement of the optical signal-to-noise ratio is obtained. With the assistance of the nonlinear mirror, we demonstrate that the spatial resolution of the sensor is improved from 3 m to 1 m, and the temperature accuracy is improved from ±0.6℃ to ±0.2℃. The theoretical analysis and the experimental data are in good agreement.
基金supported by JSPS KAKENHI Grant Numbers 25709032,26630180 and 25007652by research grants from the Iwatani Naoji FoundationSCAT Foundation and the Konica Minolta Science and Technology Foundation.
文摘Optical fibre sensors based on Brillouin scattering have been vigorously studied in the context of structural health monitoring on account of their capacity for distributed strain and temperature measurements.However,real-time distributed strain measurement has been achieved only for two-end-access systems;such systems reduce the degree of freedom in embedding the sensors into structures,and furthermore render the measurement no longer feasible when extremely high loss or breakage occurs at a point along the sensing fibre.Here,we demonstrate real-time distributed measurement with an intrinsically one-end-access reflectometry configuration by using a correlation-domain technique.In this method,the Brillouin gain spectrum is obtained at high speed using a voltage-controlled oscillator,and the Brillouin frequency shift is converted into a phase delay of a synchronous sinusoidal waveform;the phase delay is subsequently converted into a voltage,which can be directly measured.When a single-point measurement is performed at an arbitrary position,a strain sampling rate of up to 100 kHz is experimentally verified by detecting locally applied dynamic strain at 1 kHz.When distributed measurements are performed at 100 points with 10 times averaging,a repetition rate of 100 Hz is verified by tracking a mechanical wave propagating along the fibre.Some drawbacks of this ultrahigh-speed configuration,including the reduced measurement accuracy,lowered spatial resolution and limited strain dynamic range,are also discussed.
