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

] 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.