Experimental Investigation on Dynamic Properties and Noise Reduction in Actively Mode-Locked Lasers by External CW Optical Injection

We report on a detailed analysis of the effect of CW injection in an actively mode-locked laser at 780 nm, on the noise performances of the laser. The optical properties of the emitted pulse train, and the phase and amplitude noise of the RF pulse train generated after photodetection have been characterized with respect to the laser pumping rate, and to the injected power. We show that when injected, the laser exhibits a dramatic improvement of both RF phase noise and power spectrum, but at the expense of a degraded optical relative intensity noise.