Narrow linewidth distributed-feedback laser with low relative intensity noise

We fabricated a low relative intensity noise (RIN) narrow linewidth semiconductor laser module. The structure of the monolithic integrated laser chip is asymmetric phase-shifted DFB structure with the length of 1000-µm. The maximum output power reaches 26mW when the driving current is 200mA. The narrowest linewidth reaches about 35 kHz with the driving current at 150mA, and the RIN is lower than −165 dB/Hz for the frequency offset from 0.1GHz to 20 GHz in the whole current tuning range from 40 mA to 200 mA. This laser module has wide application prospects for optical sensing, digital coherent and analog communication areas.