Simple method for laser chirp diagnosis: application to the measurement of the YLF nonlinear Kerr coefficient

Abstract

We present a simple method for diagnosis, visualizing and measuring of the frequency chirp of a laser pulse. This method relies on the use of a streak-camera to temporally resolve a spatial interference pattern produced by the pulse. Analysis of the streak-camera data gives directly the functional form of the chirp including its sign and its higher order nonlinear components which can provide information on the physical process causing it, namely the self-phase modulation that the pulse undergoes in the laser medium in the course of its amplification. By studying the temporal profile of the laser coherence we have been able to measure the gain bandwidth and the third-order nonlinear coefficient for the YLF:Nd +3 laser medium: χ (3) = (1.6±0.6) × 10 −19 m 2W −1.