A Congruent‐Melting Mid‐Infrared Nonlinear Optical Vanadate Exhibiting Strong Second‐Harmonic Generation

Study of mid-infrared (mid-IR) nonlinear optical (NLO) materials is hindered by the competing requirements optimized second-harmonic generation (SHG) coefficient dij and laser-induced damage threshold (LIDT) as well harsh synthetic conditions. Herein, we report facile hydrothermal synthesis a polar NLO vanadate Cs4V8O22 (CVO) featuring quasi-rigid honeycomb-layered structure with [VO4] [VO5] polyhedra aligned parallel. CVO possesses wide IR-transparent window, high LIDT, congruent-melting behavior. It has very strong phase-matchable SHG intensities in metal family (12.0 × KDP @ 1064 nm 2.2 AGS 2100 nm). First-principles calculations suggest that exceptional responses largely originate from virtual electronic transitions within [V4O11]∞ layer; excellent transmittance arises special characteristics vibrational phonons resulting layered structure.