Optimized arrangement of non-π-conjugated PO3NH3 units leads to enhanced ultraviolet optical nonlinearity in NaPO3NH3

Here, the polar covalent group (PO 3 NH 3 ) − is identified as a novel deep-ultraviolet (DUV) NLO-active unit. Its ordered arrangement in NaPO 3 NH 3 makes this compound exhibiting the largest birefringence among DUV non-π-conjugated phosphate systems.