Second Harmonic Generation as a Tool for Measuring Mode Coupling,Pulse Length and Mode Size in Short Laser Pulses

Abstract

We report on a detailed analysis of second harmonic generation with a multi-modal beam for a non-collinear geometry. As a result some improvements for a picosecond pulse width analyser are suggested. Experimental results relative to both a free electron laser and to a mode locked Nd: YAG laser are discussed. This modified version of the pulse analyser is able to monitor, in real time, the relative pulse-to-pulse change of mode size, pulse length and mode mixing effect independently of the pulse length from femtoseconds to milliseconds.