Long-distance vector Brillouin optical time-domain analysis sensors using distributed Brillouin amplification with frequency-comb pump parallel demodulation

Abstract

We demonstrated a structure for extending repeater-less sensing distance of Brillouin optical time-domain analysis enhanced by distributed Brillouin amplification (DBA-BOTDA) through a combination with the Brillouin phase spectrum (BPS), where parallel demodulation of the frequency-comb pump can be realized. The careful structure design is implemented to perfectly suppress the impacts of various phase noises on long-distance BPS extraction. ∼98.9 km sensing distance and ∼6.5 m spatial resolution were demonstrated, with only four times frequency sweeping. The standard deviation of Brillouin frequency shift can be decreased to within ∼2 MHz by a combination of Brillouin gain spectrum and BPS.

Interference cancellation analysis of output spectrum of virtual image phased array (VIPA) and application of VIPA in spontaneous Brillouin backscattering measurement

“…rillouin spectroscopy is a powerful optical measurement technique, which has a wide range of applications in many aspects. For example, fiber optic Brillouin scattering technology has good practical value in sensing, [1][2][3][4][5] the Brillouin technology based on Fabry Poirot (F-P) etalon has great applications in material characterization, 6,7) and the Brillouin technology based on VIPA has made a major breakthrough in biomedical viscoelastic measurement. 8,9) Brillouin scattering arises from inelastic interactions between incident light waves and phonons inside the material, causing the incident light frequency to undergo a frequency shift proportional to the speed of sound in the medium.…”