Intensity noise and relaxation oscillation of a fiber-laser sensor array integrated in a single fiber

We modeled the intensity noise of a distributed-feedback fiber laser (DFB-FL) with external laser injection. The transfer function for injected power perturbation was obtained. Simulation indicates that the laser relaxation oscillation frequency is not affected by external laser injection and is determined by the laser pump power, which provides a promising way to investigate the actual pump power budget over the whole wavelength-division multiplexing (WDM) fiber-laser sensor array integrated in a single fiber. The intensity noise enhancement for each sensing unit thus can be evaluated exactly, and we observe an increase of 9dB in the intensity noise level for two DFB-FLs incorporated in a WDM fiber-laser array.