An Innoslab based Nd:YV04 MOPA system with pulse energy of 7.25 mJ at 40 kHz repetition rate and pulse duration of 11.4 ns has been used for third harmonics generation in Lithium Triborate (LBO) crystals. We report UV pulses of 8.9 ns duration at pulse energy of 1.65 mJ, which means an average power of 66 W. We have been able to show UV beam qualities (M2) of 1.7/2.4 (stable/instable direction with 90/10 knife edge method), while IR beam quality is 1.8/5.2. A sinc2-shape transversal distribution of beam intensity has been used in instable direction of the Innoslab MOPA system for conversion. Due to high average power and short pulse length at 355 nm the laser meets the demands for high-throughput micro material processing as stereolithography or edge isolation of solar cells. The thermal dependence of the conversion efficiency (due to heating power of the beam) has been investigated theoretically, using a time resolved numerical simulation model for the nonlinear process in both LBO crystals. Scaling effects of the absorption coefficients of LBO and the pulse power on the conversion efficiency are presented in this article.
[1]
Guido Mann.
Experimentelle und theoretische Untersuchungen zur Frequenzkonversion von Nd
,
2003
.
[2]
Theodor W. Hänsch,et al.
General analysis of type I second-harmonic generation with elliptical Gaussian beams
,
1997
.
[3]
Malcolm H. Dunn,et al.
Thermal dependence of the principal refractive indices of lithium triborate
,
1995
.
[4]
Keisuke Sasaki,et al.
Thermal effects on second-harmonic generation in biaxial molecular crystals
,
1999
.
[5]
Koji Kato.
Temperature-tuned 90゜phase-matching properties of LiB_3O_5
,
1994
.
[6]
D. Elliott,et al.
Ultraviolet laser technology and applications
,
1995
.
[7]
M. Okada,et al.
Influences of self-induced thermal effects on phase matching in nonlinear optical crystals
,
1971
.