We propose and experimentally demonstrate a technique using a composite-double-probe-pulse (CDPP) to eliminate the effect of polarization fading for phase-sensitive optical time-domain reflectometry (Φ-OTDR) based on ultra-weak FBG (UWFBG) array. The CDPP is composed of two optical pulses whose spatial interval is equal to twice the spatial interval of adjacent UWFBGs in the UWFBG array. One optical pulse is a long optical pulse, and the other optical pulse is composed of two continuous short optical pulses, whose polarization states are orthogonal to each other. The width of the short pulse is equal to half of the width of the normal pulse and their frequencies are different from the long pulse. By using such a method to perform the sensing for the UWFBG array, distributed quantitative measurement can be realized with only direct detection scheme and the influence of polarization fading in the demodulation of signal is thoroughly eliminated.
|Proceedings of SPIE - International Society for Optical Engineering
|Published - 14 Feb 2019
|17th International Conference on Optical Communications and Networks, ICOCN 2018 - Zhuhai, China
Duration: 16 Nov 2018 → 19 Nov 2018
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- Optical fiber sensors
- phase demodulation
- polarization fading
- ultra-weak FBG array