The Next-Generation of Nonlinear Optical Materials: Rb₃Ba₃Li₂Al₄B₆O₂₀F—Synthesis, Characterization, and Crystal Growth

Nonlinear optical (NLO) materials are of intense academic and technological interest attributable to their ability to generate coherent radiation over a range of different wavelengths. The requirements for a viable NLO material are rather strict, and their discovery has mainly been serendipitous. This study reports synthesis, characterization, and, most importantly, growth of large single crystals of a technologically viable NLO material—Rb₃Ba₃Li₂Al₄B₆O₂₀F. Through the judicious selection of cations, Rb₃Ba₃Li₂Al₄B₆O₂₀F exhibits a 3D structure that facilitates the growth of large single crystals along the optical axis direction. Measurements on these crystals indicate that Rb₃Ba₃Li₂Al₄B₆O₂₀F exhibits a moderate birefringence of 0.057 at 1064 nm enabling Type I phase-matching down to 243 nm. Theoretical calculations indicate the symmetry adapted mode displacement (SAMD) parameter scales with the second-harmonic generation intensity.