Growth and characterization of CsB3O5 crystals without scattering centers

Abstract

CsB₃O₅ (CBO) single crystals without scattering centers have been successfully grown from the Cs₂O–B₂O₃–MoO₃ ternary system by the top-seeded solution growth method. The suitable region for CBO crystal growth was investigated by growth experiments, viscosity and volatility measurements, which confirmed that the optimal molar ratio of Cs₂O : B₂O₃ : MoO₃ was 2 : 3 : 2.5. By carefully controlling growth parameters, including the temperature gradient in the axis, rotation rate, cooling rate, and seed direction, a free of scattering centers CBO crystal with dimensions up to 29 × 31 × 47 mm³ has been obtained. The grown CBO crystals possess high optical quality. The full-width at half-maximum (FWHM) of the rocking curve is 0.0057°, and the optical homogeneity is at the level of 10⁻⁶ cm⁻¹. The optical absorption at the critical wavelengths of 1064 and 532 nm was measured to be 200 and 60 ppm cm⁻¹, respectively. The laser-induced damage threshold (LIDT) at λ = 1.064 nm and τ = 5.0 ns is about 4.50 GW cm⁻². Moreover, a high-power 278 nm ultraviolet (UV) laser through fourth harmonic generation (FOHG) of a diode-pumped 1112 nm Nd:YAG laser has been demonstrated in CBO crystal for the first time.