An optimized method to suppress the spontaneous MI-induced phase noise in the interferometric fiber sensing system

In the interferometric fiber sensing system, the spontaneous modulation instability (MI) initiating from the amplified spontaneous emission (ASE) noise is a main limitation factor of the maximum input power. The spontaneous MI leads to the serious phase noise, which degrades the system performance. Here, we propose an optimized method to suppress the spontaneous MI by controlling the phase difference. Frist, we impose weak coherent sidebands, which can suppress the spontaneous MI by exciting the induced MI. Subsequently, we carefully control the phase difference between weak coherent sidebands and pump. The results show that the phase noise can be suppressed by controlling the phase difference. The optimized phase noise can is low as -99 dB. Compared to the system without phase difference control, the phase noise is reduced by -3 dB (re 1 rad / &radic;<i>Hz</i> ).