A new method is proposed and demonstrated for measuring the phase noise (pulse timing fluctuations) of mode-locked lasers. The instantaneous phases of the pulse intensity are extracted in a time domain, and the phase-noise power spectral density is calculated from the demodulated signals. Compared with the conventional method based on the single-sideband phase-noise measurement, the proposed method has a larger dynamic range and a wider frequency span. The phase noise of a mode-locked Cr:LiSAF laser is measured for 50-mHz–1-MHz Fourier frequencies.
© 1998 Optical Society of America
(140.4050) Lasers and laser optics : Mode-locked lasers
(140.7090) Lasers and laser optics : Ultrafast lasers
(320.0320) Ultrafast optics : Ultrafast optics
(350.5030) Other areas of optics : Phase
Hidemi Tsuchida, "Wideband phase-noise measurement of mode-locked laser pulses by a demodulation technique," Opt. Lett. 23, 286-288 (1998)