Time-interval analysis of laser-pulse-timing fluctuations

A new technique has been proposed and demonstrated for measuring the pulse-timing fluctuations of mode-locked lasers at low Fourier frequencies. The time interval between the laser pulses is precisely measured by use of zero-dead-time counters referenced to a stable atomic oscillator. By combination of this method with the time-domain demodulation technique, the phase-noise power spectral density of a mode-locked Cr:LiSAF laser has been estimated for the 1-mHz-1-MHz Fourier frequency range, with a 240-dB dynamic range. (C) 1999 Optical Society of America OCIS codes: 140.3480, 140.3580, 140.4050, 140.7090, 320.7090.