We established a complete model and relationship between laser source characteristics and measurement accuracy of high precision fiber microprobe sensor(FMS)based on phase generated carrier demodulation.The laser carr...We established a complete model and relationship between laser source characteristics and measurement accuracy of high precision fiber microprobe sensor(FMS)based on phase generated carrier demodulation.The laser carried out high-bandwidth frequency modulation to improve the measurement speed.Meanwhile,the laser also carried out large-amplitude frequency modulation to eliminate tens of nanometers of nonlinear error,thus improving the measurement accuracy.Further,the laser center wavelength is required to be stabilized under the above modulation to achieve a high measurement stability.The conflict between laser frequency modulation and central stability is revealed and analyzed alongside the distortion of measurement accuracy.A modified frequency stabilization method for laser source under high-bandwidth and large-amplitude modulation is proposed for improving measurement accuracy to realize sub-nanometer precision.The experimental results showed that when the modulation bandwidth was 1 MHz and maximum modulation amplitude was 2.61 GHz,the distributed feedback laser central wavelength stability was 2.9×10^(−10)(τ=1s)according to Allan variance.Additionally,the relative expanded uncertainty of the laser wavelength was demonstrated to be superior to 5×10^(−8)(k=2)within 3 hr,which was at least one order of magnitude higher than that of the traditional method.The resolution and stability of FMS is better than 0.4 nm,and the nonlinear error is reduced from tens of nm to 0.8 nm,which meets the requirements of sub-nanometer measurements.展开更多
Double-pass forward and double-pass backward erbium-doped super-fluorescent fiber sources（EDSFSs） were combined in one configuration.A 980 nm laser diode pumped the same erbium-doped fiber from both directions using...Double-pass forward and double-pass backward erbium-doped super-fluorescent fiber sources（EDSFSs） were combined in one configuration.A 980 nm laser diode pumped the same erbium-doped fiber from both directions using a coupler as a power splitter.The double-pass configuration was achieved by coating the fiber end face.Firstly,an optimal fiber length was found to obtain a high stability of output light wavelength with pump power, and then 1530/1550 nm wavelength division multiplexing was used for spectrum planarization,which expanded the bandwidth to more than 22 nm.The final step was a test of temperature stability.The results show that the rate of the central wavelength change kept to below 3.5 ppm/℃in the range of -40 to 60℃and 1-2 ppm/℃in the range of 20-30℃.Considering all the three factors of the fiber optic gyro applications,we selected 80 mA as the pump current,in which case the central wavelength temperature instability was calculated as 2.70 ppm/℃, 3 dB bandwidth 22.85 nm,spectral flatness 0.2 dB,output power 5.17 mW and power efficiency up to 9.92%.This experimental result has a significant reference value to the selection of devices and proper design of ED-SFSs for the application of high-precision fiber optic gyroscopes.展开更多
基金supported by the National Key Research and Development Projects of China(No.2022YFF0705802)National Natural Science Foundation of China(62305090)+1 种基金China Postdoctoral Science Foundation(2023M730883)Fellowship of China National Postdoctoral Program for Innovative Talents(BX20230478).
文摘We established a complete model and relationship between laser source characteristics and measurement accuracy of high precision fiber microprobe sensor(FMS)based on phase generated carrier demodulation.The laser carried out high-bandwidth frequency modulation to improve the measurement speed.Meanwhile,the laser also carried out large-amplitude frequency modulation to eliminate tens of nanometers of nonlinear error,thus improving the measurement accuracy.Further,the laser center wavelength is required to be stabilized under the above modulation to achieve a high measurement stability.The conflict between laser frequency modulation and central stability is revealed and analyzed alongside the distortion of measurement accuracy.A modified frequency stabilization method for laser source under high-bandwidth and large-amplitude modulation is proposed for improving measurement accuracy to realize sub-nanometer precision.The experimental results showed that when the modulation bandwidth was 1 MHz and maximum modulation amplitude was 2.61 GHz,the distributed feedback laser central wavelength stability was 2.9×10^(−10)(τ=1s)according to Allan variance.Additionally,the relative expanded uncertainty of the laser wavelength was demonstrated to be superior to 5×10^(−8)(k=2)within 3 hr,which was at least one order of magnitude higher than that of the traditional method.The resolution and stability of FMS is better than 0.4 nm,and the nonlinear error is reduced from tens of nm to 0.8 nm,which meets the requirements of sub-nanometer measurements.
文摘Double-pass forward and double-pass backward erbium-doped super-fluorescent fiber sources（EDSFSs） were combined in one configuration.A 980 nm laser diode pumped the same erbium-doped fiber from both directions using a coupler as a power splitter.The double-pass configuration was achieved by coating the fiber end face.Firstly,an optimal fiber length was found to obtain a high stability of output light wavelength with pump power, and then 1530/1550 nm wavelength division multiplexing was used for spectrum planarization,which expanded the bandwidth to more than 22 nm.The final step was a test of temperature stability.The results show that the rate of the central wavelength change kept to below 3.5 ppm/℃in the range of -40 to 60℃and 1-2 ppm/℃in the range of 20-30℃.Considering all the three factors of the fiber optic gyro applications,we selected 80 mA as the pump current,in which case the central wavelength temperature instability was calculated as 2.70 ppm/℃, 3 dB bandwidth 22.85 nm,spectral flatness 0.2 dB,output power 5.17 mW and power efficiency up to 9.92%.This experimental result has a significant reference value to the selection of devices and proper design of ED-SFSs for the application of high-precision fiber optic gyroscopes.
