Cs2CdV2O6Br2: A Mid-Infrared Nonlinear Optical Vanadate Containing Both d0/d10 Transition Metal Cations and Bromine Anions

Exploration of new mid-infrared nonlinear optical crystals in oxides is a great challenge and significant for the next generation of all-solid-state laser technology. In this work, a novel fresnoite-like vanadate cadmium oxybromide, Cs2CdV2O6Br2 (CCVB), is successfully designed and synthesized through the introduction of both d0 V5+ and d10 Cd2+ transition metal cations and bromine anions. CCVB exhibits strong second-harmonic generation (SHG) responses of 13.5 × KH2PO4 (KDP) at 1064 nm and 1.2 × AgGaSe2 (AGS) at 2.1 μm as well as an ultrahigh laser-induced damage threshold (75 × AGS at 1064 nm). Furthermore, CCVB can achieve phase matching under both 1064 nm and 2.1 μm laser pumping. Moreover, the infrared transparency cutoff edge of CCVB can reach up to 10.4 μm, displaying a bright prospect applied for mid-infrared laser frequency conversion. The large macroscopic SHG coefficients of CCVB are interpreted from first-principles computation. This research provides a practical way for the design of new vanadium-based oxides for mid-infrared nonlinear optical applications.