A Congruent‐Melting Mid‐Infrared Nonlinear Optical Vanadate Exhibiting Strong Second‐Harmonic Generation
Chao Wu, Xingxing Jiang, Lin Lin, Yilei Hu, Tianhui Wu, Zheshuai Lin, Zhipeng Huang, Mark G. Humphrey, Chi Zhang
Abstract
Abstract Study of mid‐infrared (mid‐IR) nonlinear optical (NLO) materials is hindered by the competing requirements of optimized second‐harmonic generation (SHG) coefficient d ij and laser‐induced damage threshold (LIDT) as well as the harsh synthetic conditions. Herein, we report facile hydrothermal synthesis of a polar NLO vanadate Cs 4 V 8 O 22 (CVO) featuring a quasi‐rigid honeycomb‐layered structure with [VO 4 ] and [VO 5 ] polyhedra aligned parallel. CVO possesses a wide IR‐transparent window, high LIDT, and congruent‐melting behavior. It has very strong phase‐matchable SHG intensities in metal vanadate family (12.0 × KDP @ 1064 nm and 2.2 × AGS @ 2100 nm). First‐principles calculations suggest that the exceptional SHG responses of CVO largely originate from virtual electronic transitions within [V 4 O 11 ] ∞ layer; the excellent optical transmittance of CVO arises from the special characteristics of vibrational phonons resulting from the layered structure.