Na_2CsBe_6B_5O_15: An Alkaline Beryllium Borate as a Deep-UV Nonlinear Optical Crystal

摘要

ABSTRACT: A new deep-UV nonlinear optical crystal, Na_2CsBe_6B_5O_15, has been grown through spontaneous crystallization with a molten flux based on Na_2O-C-s_2O-B_2O_3. Na_2C_5Be_6B_5O_15 contains two-dimensional alveolate beryllium borate layers [Be_2O_5]∞ that are bridged via planar [BO_3] groups. UV-vis diffuse reflectance analysis on a powder sample of Na_2C_5Be_6B_5O_15 indicates that the short-wavelength absorption edge of Na_2CsBe_6B_sO_15 is below 200 nm. Second-harmonic generation (SHG) on the powder sample was measured with a 1064 nm laser using the Kurtz and Perry technique, which showed that Na_2Cs-Be_6B_5O_15 is a phase-matchable material, and its measured SHG coefficient is ~1.17 times as large as the d_36 coefficient of potassium dihydrogen phosphate. The relatively larger SHG coefficient of Na_2C_sBe_6B_5O_15 originates from its shorter distance between the adjacent layers bridged via the small [BO_3] groups.