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

Area of Science:

• Optical Engineering
• Spectroscopy
• Signal Processing

Background:

• Stimulated Brillouin scattering optical spectrum analyzers (SBS-OSAs) offer sub-picometer resolution, crucial for optical communication and sensing.
• Sensitivity in SBS-OSAs is currently limited by amplified Brillouin scattering (ABS) and Rayleigh backscattering (RB) noise.
• Effective noise reduction is essential for unlocking the full potential of SBS-OSA technology.

Purpose of the Study:

• To analyze the sources and characteristics of noise in SBS-OSAs.
• To propose and experimentally validate a novel noise suppression method for SBS-OSAs.
• To enhance the sensitivity and polarization independence of SBS-OSA systems.

Main Methods:

• Detailed analysis of noise sources, including ABS and RB noise, within the SBS-OSA.
• Development and implementation of a noise suppression technique utilizing polarization filtering.
• Experimental validation of the proposed method using a stimulated Brillouin scattering narrowband optical filter (SBS-NBOF).

Main Results:

• A noise figure (NF) reduction of 7-10 dB was achieved in the SBS-NBOF.
• Sensitivity improvements of 7.6-9.4 dB for single-frequency signals and 7.6-9.2 dB for periodic signals were demonstrated.
• The proposed method exhibited polarization independence, with a root mean square error (RMSE) of 0.22 dBm across different input polarization states.

Conclusions:

• The polarization filtering method effectively suppresses noise in SBS-OSAs, significantly enhancing system sensitivity.
• The achieved noise reduction and sensitivity improvements are critical for advancing optical communication and sensing applications.
• The polarization independence of the method ensures robust performance across various operating conditions.