Seeded nanosecond Q-switched Nd:YAG lasers working with an unstable resonator and a variable-reflectivity-mirror are widely used for they represent useful sources for stable and repeatable light-matter-interaction experiments. Moreover, in most setups, the fundamental wavelength is converted to higher harmonics. When the injection seeder is turned off, random longitudinal mode beating occurs in the cavity, resulting in strong variations of the temporal profile of the pulses. The generated spikes can then be ten times higher than the maximum of equivalent seeded pulses. This strong temporal incoherence is shown to engender spatial incoherence in the focal plane of such unseeded pulses leading to an instantaneous angular displacement of tens of µrad. This effect is even more pronounced after frequency conversion.

Date Published: 23 November 2015
PDF: 14 pages
Proc. SPIE 9632, Laser-Induced Damage in Optical Materials: 2015, 96321S (23 November 2015); doi: 10.1117/12.2195470

Published in SPIE Proceedings Vol. 9632:
Laser-Induced Damage in Optical Materials: 2015
Gregory J. Exarhos; Vitaly E. Gruzdev; Joseph A. Menapace; Detlev Ristau; MJ Soileau, Editor(s)