Deconvolutional Method Utilizing Power Variable Point Spread Function for Resolution Degradation Mitigation in SBS-Based Optical Spectrum Analyzer

High-resolution optical spectroscopy is a significant approach to reveal the inherent laws of devices and systems. Although optical spectrum analyzer (OSA) based on stimulated Brillouin scattering (SBS) has achieved a resolution of similar to 10 pm, when the signal power increases, the Brillouin gain spectrum (BGS) will saturate and cause resolution degradation. In order to solve this problem, we introduce shape factor k to describe the variation of BGS with signal power, and adopt the BGS as the point spread function (PSF). Then the signal is divided into several intervals with equal frequency spacing, where the BGS does not change. On this basis, we perform the Jansson-Van Cittert (JVC) algorithm to complete deconvolution in each interval with power variable PSF. The proposed method is used to test the periodic signal in SBS-OSA. Experimental results show that the proposed method can improve the spectral resolution from 22 MHz to 11 MHz when the frequency interval is 14 MHz and the signal power is -5 dBm.