Measurement of mode-locked laser timing jitter by use of phase-encoded optical sampling

The phase-noise characteristics of a harmonically mode-locked fiber laser a re investigated with a new measurement technique called phase-encoded optic al sampling. A polarization-maintaining ring laser is mode locked by use of the short-pulse electrical output of a resonant-tunneling diode oscillator , enabling it to produce 30-ps pulses at a 208-MHz repetition rate. The int erferometric phase-encoded sampling technique provides 60-dB suppression of amplitude-jitter noise and allows supermode phase noise to be observed and quantified. The white-noise pulse-to-pulse timing jitter and the rms super mode timing jitter of the laser are measured to be less than 50 and 70 fs, respectively. (C) 2001 Optical Society of America.