Third harmonic generation of a mode-locked laser in a resonant enhancement cavity

Summary form only given. There are many applications for high efficiency third harmonic generation of solid state lasers to the ultraviolet region of the spectrum including pumping of optical parametric oscillators in the visible region of the spectrum and materials processing. Following the approach of Persaud (see IEEE J. Sel. Top. Quantum Electron., vol. 7, p. 1253, 1990) we describe the use of an optical cavity to enhance the nonlinear conversion efficiency. The pump laser employed is a diode-pumped Nd:YVO/sub 4/ source. Third harmonic generation is accomplished using two phase matched LiB/sub 3/O/sub 5/ (LBO) crystals. The first crystal is non-critically phase matched Type I doubling and the second is angle tuned sum-frequency Type II mixing thereby preserving the original polarisation of the fundamental.