Measurement of the shot-to-shot carrier-envelope phase slip of femtosecond laser pulses

Abstract

We measure the shot-to-shot slip of the carrier-envelope phase (CEP) of mode-locked femtosecond laser pulses by using a 2f-to-f self-referencing interferometer. The 2f-to-f interferometer, composed of a one-octave spectrum generator and a nonlinear interferometer, yields the beat signal between the 2f-component and the second harmonic of the f-component generated in a nonlinear crystal. The CEP slip between two successive laser pulses is successfully measured from the beat frequency with a phase jitter of 2.7 mrad. We also control the shot-to-shot CEP slip from 0 to similar to pi by adjusting either the intracavity prism insertion or the pumping power of the laser oscillator. This measurement offers basic information for the design of a feedback control loop to stabilize the shot-to-shot CEP slip of mode-locked laser pulses.