We demonstrated an ultra-low noise polarization-maintaining (PM) single frequency fiber laser (SFFL) at 2 μm. By suppressing the pump relative intensity noise (RIN) using a feedback loop control, the RIN and frequency noise of the SFFL are simultaneously reduced, and the reduction is about 3 - 15 dB and 3 - 8.4 dB, respectively. After two stage Tm3+-doped PM fiber amplifier, the output power reached about 5 W. Meanwhile, the frequency noise almost has no increases, which is still below 100 Hz/√Hz after 13 Hz. And the frequency-tunable range is approximately 2 GHz with frequency response of 46 MHz/V.
|