Measurements of first-passage-time distributions in laser transients near threshold

The first-passage-time (FPT) problem for the time evolution of the optical field produced by a Q-switched laser has been investigated theoretically and experimentally in the neighborhood of the laser threshold. Experiments were performed on a He–Ne laser operating near threshold in its steady state. Measurements for several operating points were made. Q switching was achieved with the help of an intracavity acousto-optic modulator. The measured FPT distributions are compared with the approximate analytic results for the FPT distribution and the numerical solutions of the laser Fokker–Planck equation based on the van der Pol oscillator model of the laser.