Sulfamide: A Promising Deep‐Ultraviolet Nonlinear Optical Crystal Assembled from Polar Covalent [SO2(NH2)2] Tetrahedra

For the first time, the polar covalent tetrahedron [SO2 (NH2 )2 ] is revealed as a new deep-ultraviolet (DUV) nonlinear optical (NLO)-active unit according to theoretical calculations. Furthermore, sulfamide consisting of polar [SO2 (NH2 )2 ] units was confirmed as an excellent candidate as a DUV NLO crystal. Sulfamide provides the optimal balance between composition, structure, and properties, in addition to a very short absorption of 160 nm. It achieves multiple optical performance records for non-π-conjugated DUV NLO materials, including the strongest second harmonic generation (SHG) efficiency (about 4 times that of KDP), the largest birefringence (obv.: 0.07@589.3 nm) and the shortest SHG wavelength predicted as 188 nm.