Multi-longitudinal mode fiber laser sensor system with high signal-to-noise ratio based on laser modes control

Abstract

A multi-longitudinal mode fiber laser sensor (MLMFLS) system with high signal-to-noise ratio (SNR) is proposed. To the best of authors' knowledge, this is the highest SNR ever reported by MLMFLS system. The laser sensor consists of a narrow-band fiber Bragg grating (FBG), erbium-doped fiber (EDF) and an optical reflector. The FBG controls the number of laser modes which excited by laser sensor. Beat frequency signals (BFS) modulated by applied measurand are generated by those laser modes and their SNR are controlled by the FBG. Measurement results show the BFS have SNR of 65.0 dB, accuracy of ± 2.0 με, and stability of 0.4 kHz, which demonstrate its high SNR, accuracy and stability.