KHC2O4•B(OH)3: A nonlinear optical crystal with large birefringence in the short-wavelength ultraviolet region

초록

Exploring nonlinear optical crystals with large birefringence in the short-wavelength ultraviolet (SWUV) regions (<= 300 nm) is a valuable pursuit. Herein, KHC2O4 center dot B(OH)(3), which is composed of infinite [HC2O4](-) and [B(OH)(3)] chains, was successfully grown via the slow evaporation method. The [HC2O4](-) and [B(OH)(3)] chains endow KHC2O4 center dot B(OH)(3) with the largest birefringence (0.164@1064 nm) of all B(OH)(3)-containing compounds that have been reported in the SWUV regions. Moreover, it possesses a moderate second-harmonic generation response (0.3 x KH2PO4) and a short UV cutoff edge of 254 nm. The electron localization function diagram indicates the large birefringence originates from the HC2O4 and B(OH)(3) groups. This work provides a new method to investigate crystals with large birefringence in the B(OH)(3)-based oxalate system.

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