Abstract

Measurement of femtosecond pulses without any reference requires three successive steps: a linear filter, a non linear interaction (e.g. SHG) and a spectral measurement of the output [1]. As previously demonstrated, the linear filtering can be performed using a pulse shaper, such as an acousto-optic programmable dispersive filter (AOPDF) [2]. Since a significant number of CPA amplifiers now include a pulse shaper in their front-end, it is highly convenient to use such a device not only to correct but also to characterize the amplified pulses by adding at the back-end a nonlinear element and a spectral detector. In this paper, we demonstrate experimentally a new phase-only measurement technique called Local Spectral Compression (LSC) on a CPA laser system (CEA Saclay) by inserting an AOPDF in front of the last three-pass amplifier and a nonlinear BBO crystal at the output. The second harmonic signal is recorded with a spectral detector.

© 2009 IEEE