Analysis of bandwidth-reduced local oscillator in Brillouin optical time domain reflectometry

Yun-Qi Hao; Qing Ye; Zheng-qing Pan; Hai-wen Cai; Rong-hui Qu

doi:10.1117/12.904179

29 November 2011 Analysis of bandwidth-reduced local oscillator in Brillouin optical time domain reflectometry

Yun-Qi Hao, Qing Ye, Zheng-qing Pan, Hai-wen Cai, Rong-hui Qu

Proceedings Volume 8311, Optical Sensors and Biophotonics III; 831120 (2011) https://doi.org/10.1117/12.904179
Event: SPIE/OSA/IEEE Asia Communications and Photonics, 2011, Shanghai, China

Abstract

A local oscillator for coherent detection of backward Brillouin scattering in Brillouin optical time domain reflectometry (BOTDR) has been analyzed. A ring Brillouin fiber laser, whose Brillouin gain media is 70m high-nonlinear-fiber (HNLF), is used as local oscillator of coherent detection. The BFL operates at 1549.06nm red-shifted 0.084nm from the pump laser. As to Brillouin light, The detection frequency is reduced from ~11GHz of direct detection to ~420MHz of heterodyne detection in this paper. Self-lasing cavity-modes of BFL impose the "burr" intervalled at 2.5MHz on the frequency domain analysis of the beat-frequency siganl. Signal-to-noise ratio (SNR) of beat-frequency signal decreases greatly, resulting to Lorentzian fitting with error. By adjusting variable optical attenuator (VOA) to increase the cavity loss in the fiber ring cavity, the self-lasing cavity-modes will be eliminated and a stable Brillouin laser will be obtained. The frequency estimation accuracy is improved greatly.

Citation Download Citation

Yun-Qi Hao, Qing Ye, Zheng-qing Pan, Hai-wen Cai, and Rong-hui Qu "Analysis of bandwidth-reduced local oscillator in Brillouin optical time domain reflectometry", Proc. SPIE 8311, Optical Sensors and Biophotonics III, 831120 (29 November 2011); https://doi.org/10.1117/12.904179

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