Growth and optical properties of (K0.62Na0.38)2Al2B2O7 crystal

Abstract Large bulk of (K1−xNax)2Al2B2O7 crystal with reactants of K2CO3 and Na2CO3 in a molar ratio of 1:1 was grown by a top seeded solution growth (TSSG) method. The flux systems for the growth of (K1−xNax)2Al2B2O7 single crystal were investigated. (K1−xNax)2Al2B2O7 single crystal could be easily grown from NaF + LiF flux system with the molar ratio of NaF: LiF = 1:1. The X-ray powder diffraction showed that (K1−xNax)2Al2B2O7 crystal adopted the same structure type of KABO. The molecular formula of the as-grown crystal was (K0.62Na0.38)2Al2B2O7 determined by ICP-AES. The transmittance of (K0.62Na0.38)2Al2B2O7 crystal increased below 300 nm compared with those of fewer amounts of Na+ substitution KABO crystals. The conversion efficiency of the fourth harmonic generation with a specimen 6.74 mm in length reached 20.1% for a picosecond mode-locked Nd:YAG laser. With an input power of 26.8 W, a 353 mW average output power was obtained through fourth harmonic generation of an nanosecond Q-switched Nd:YAG laser.