Theoretical and experimental study of suppressing stimulated Brillouin scattering and phase noise in interferometric fiber sensing systems with phase modulation.

Abstract

The effect of phase modulation on the phase noise in remote interferometric fiber sensing systems is analyzed in both theory and experiment. A matching condition between the modulation frequency and optical delay difference is derived to choose the matching modulation frequency. The matching modulation frequency for an interferometer with 5 m optical-path difference is 60 MHz and its integer harmonic frequencies. By matching the condition, the phase modulation method can suppress the stimulated Brillouin scattering in an interferometric fiber sensing system effectively without bringing excess phase noise, which is verified by the experiment. The results indicate that the maximum input power of the system can be increased effectively, which has great potential in the design of remote interferometric fiber-sensing systems.