Phase-noise Reduction In A Passively Mode-locked Fiber Ring Laser

We have estimated the phase-noise of a mode-locked fiber ring laser. The generated laser pulses have 270 fs duration with a repetition rate of 45.4 MHz, which is pumped by a laser diode. Afeedback loop is used to reduce the intensity fluctuation of the pump source and the laser cavity is clmely controlled for the air fluctuation in a sealed box. The phase-noise of the laser is measured in the frequency domain by using a radio-frequency spectrum analyzer. The timing jitter between pulse:-to-pulse was below 0.73 ps in an integrated frequency offset from 30 Hz to 3 kHz.