Abstract

The high-average power, short-pulse electro-optic switch has permitted the compact, diode-pumped power slab oscillator to be efficiently frequency doubled, extending the frequency agility of this high-efficiency, high brightness source. As previously reported, we have demonstrated 250 W of average power generated by means of high-repetition-rate (~3 kHz), short-pulse (~25 ns) Q-switching by using a thermally compensated LiNbO₃ electro-optic modulator.¹ However, several gated ranging applications require even shorter pulse widths (5 ns FWHM) at high average power (100 W); such pulse widths are difficult to achieve in a typical Q-switched architecture. To meet these goals, we have demonstrated average-power cavity dumping of a diode-pumped slab laser. Since the low surface-damage threshold of LiNbO₃ may be a problem at the high intracavity fluences, we have investigated using KTP as the electro-optic-switch material. KTP is a nonlinear crystal with electro-optic coefficients comparable to those of DKDP and LiNbO₃ and with surface-damage thresholds 3-5 times that of LiNbO₃. Typical flux-grown KTP exhibits optical-index inhomogeneities and an electro-chromic-damage effect. As reported previously, the solution to both of these problems has permitted the use of KTP in a dual-crystal, thermally compensated switch configuration.² Using a high-optical-homogeneity crystal obtained from HOYA Corp., we have constructed two 6×11-mm²-aperture (16-mm-propagation-length) thermally compensated KTP Q-switches.

© 1995 Optical Society of America