Generation and Measurement of Ultrashort Light Pulses

Abstract

An experimental arrangement for the generation of ultrashort light pulses by mode locking of a Nd:glass laser with a saturable dye and their half‐width measurement is described. The pulses, being too short for determining their duration by conventional means, were studied by measuring their autocorrelation function with a method based on optical second‐harmonic generation. Measurements were made for two positions of the dye cell within the resonator; first, at some small distance from one of the mirrors and second, with one mirror forming one of the walls of the dye cell. For the former dye cell position the output considered of two or more pulses with a half‐width of approximately 30 psec, separated by about 120 psec. With the latter arrangement however, short single pulses were generated having a duration of 8–12.5 psec. In addition this arrangement greatly improved the reproducibility of the pulses and the stability of the output from flash to flash.