Polarization separation assisted opto-mechanical time-domain analysis with sub-meter resolution

Optomechanical time-domain analysis (OMTDA) is a novel approach to measure distributed acoustic impedance of surrounding media with a high spatial resolution based on coherent forward stimulated Brillouin scattering probing. However, the spatial resolution is still limited by the polarization noise and influence of activation pulse. In this Letter, we propose a polarization separation based OMTDA to further improve the resolution. By isolating the acoustic activation and probing process in orthogonal polarization states, the backward Brillouin scattering of an activation pulse is effectively suppressed. Accompanied with the reduced polarization fluctuation brought by polarization-maintaining fiber, a spatial resolution of 0.8 m is experimentally demonstrated over a 34-m-long fiber and the precise distinction between air and alcohol is realized.