CsAlB3O6F: A Beryllium-Free Deep-Ultraviolet Nonlinear Optical Material with Enhanced Thermal Stability
The design of new beryllium-free deep-ultraviolet nonlinear optical materials is important but challenging. Here, we described a new strategy to search for such materials based on rational selection of fundamental structural units. By combining asymmetric AlO3F tetrahedra and π-conjugated B3O6 rings, a new aluminum borate fluoride, CsAlB3O6F was obtained. It exhibits excellent linear and nonlinear optical properties including a high optical transmittance with absorption edge shorter than 190 nm, large second harmonic generation intensities (2.0 × KH2PO4, KDP), and suitable birefringence for phase-matching under 200 nm. It also has good thermal stability and can be synthesized easily in the open system.