Research on the Gain Saturation Induced Noise in an Optical Fiber Sensing System

In an optical fiber sensing time division multiplexing (TDM) system, when the optical pulse with high peak power and low repetition rates is boost amplified, it is prone to be gain saturation and pulse distortion. The paper analysed their effects on the intensity and phase noises, and the results show that the pulse distortion induced noise is mainly down-converted relative intensity noise (RIN) lines spectra caused by the gain jitter. Then the RIN lines are converted into corresponding phase noise lines by the interferometer, which finally cause false signals in the sensor system. However in the case of saturated gain and pulse distortion, the increase of noise background is insignificant. Basing on the above results, several noise suppression schemes have been proposed, which will provide guidance for the design of large-scale remote sensing systems in the future.