Improved fourth harmonic generation in β-BaB2O4 by tight elliptical focusing perpendicular to walk-off plane
✍ Scribed by Masakuni Takahashi; Akira Osada; Alex Dergachev; Peter F. Moulton; Marilou Cadatal-Raduban; Toshihiko Shimizu; Nobuhiko Sarukura
- Publisher
- Elsevier Science
- Year
- 2011
- Tongue
- English
- Weight
- 346 KB
- Volume
- 318
- Category
- Article
- ISSN
- 0022-0248
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✦ Synopsis
We present a scheme using beta-barium borate (BBO) crystal to maximize fourth-harmonic ultraviolet (UV) generation from high-power, kHz-range repetition rate Nd lasers by reducing thermal dephasing during the phase matching process. Thermal dephasing due to nonlinear absorption (NLA) induced by two-photon absorption of high peak power fourth-harmonic UV radiation is reduced by minimizing second-and fourth-harmonic beam overlap through tight elliptical focusing perpendicular to the walk-off plane, leading to multi-watt, kHz-range repetition rate UV generation in BBO crystal. With such beam shaping, nearly 5 W at 10 kHz of 262-nm UV radiation is generated using an 8-mm long BBO crystal. The results of our investigation show an efficient way of achieving multi-watt UV generation at kHz-range repetition rate.