Walk-off Compensated 266-nm Generation with Two β-BaB₂O₄ Crystals

Abstract

A walk-off compensation arrangement of two β-BaB₂O₄ (BBO) crystals is used to generate 266-nm (4ω) light from 532-nm (2ω) light that is produced by an intracavity frequency-doubled Nd:YAG laser. While this arrangement is effective in terms of conversion efficiency, back conversion from 4ω to 2ω can easily occur in the second BBO when the phase difference between the 2ω and 4ω in the air gap between the two crystals shifts to π. Performance characteristics are discussed here with particular reference to the angular bandwidth of the second BBO.