A noise suppression method based on polarization filtering and its application in SBS-OSA

The optical spectrum analyzer based on stimulated Brillouin scattering (SBS-OSA) has important application potential in the field of optical communication and optical sensing due to its sub-picometer resolution. However, the sensitivity is limited by amplified Brillouin scattering (ABS) noise and Rayleigh backscattering (RB) noise. Therefore, the source and characteristics of noise in SBS-OSA are analyzed, and a noise suppression method based on polarization filtering is proposed in this paper. Experiments demonstrate a 7-10 dB noise figure (NF) reduction in the SBS narrowband optical filter (SBS-NBOF). Sensitivity improvements of 7.6-9.4 dB (single-frequency signal) and 7.6-9.2 dB (periodic signals) are achieved in the application of SBS-OSA. Furthermore, the root mean square error (RMSE) of sensitivity under different input polarization states is 0.22 dBm after processing, indicating polarization independence of the proposed method.