A promising ultraviolet nonlinear optical crystal: Rb3Ba3Li2Al4B6O20F—crystal growth, physical properties, and 266 nm laser generation

Abstract

Ultraviolet laser is an indispensable technology applied in the fields of photolithography, micromachining, and laser prototyping. To date, only β-BaB₂O₄ and CsLiB₆O₁₀ are commercially available for direct fourth harmonic generation (266 nm) output of a fundamental wavelength (1064 nm). However, they suffer from the drawbacks of large walk-off angles or highly hygroscopic nature, respectively. Herein, the crystal growth, physical properties, and 266 nm laser generation of Rb₃Ba₃Li₂Al₄B₆O₂₀F (RBLABF) were systematically evaluated. The results indicate that RBLABF can be grown as high-quality and large-size single crystals. Also, it exhibits excellent comprehensive performances, i.e., non-deliquescence, moderate birefringence (0.06@532 nm), short phase-matching wavelength (262 nm), large NLO coefficient (0.46 pm V⁻¹), small walk-off angle (0.74°@532 nm) and large acceptance angle (10.56 mrad mm@532 nm), small anisotropic thermal expansion, and desirable specific heat and thermal conductivity. More importantly, the 266 nm laser was successfully output through an RBLABF crystal device. These make RBLABF a competitive UV NLO crystal for 266 nm laser generation.