Reduction of phase instability in a mode-locked argon laser

Timing fluctuations in a mode-locked laser cause phase noise sidebands on the carrier and its harmonics in the frequency spectrum of the output of the laser. We reduced the phase noise of the output of a mode-locked argon laser by 40 dB, 80 Hz away from the carrier, as measured on its twentieth harmonic by simply replacing the commonly supplied rf synthesizer by a higher performance frequency generator. Applications demanding reduced timing fluctuations or reduced phase noise include synchronization of lasers and cross-correlation detection as in phase fluorometry.