KMg(H2O)PO4: A Deep-Ultraviolet Transparent Nonlinear Optical Material Derived from KTiOPO4

Discovery of new nonlinear optical (NLO) crystals, especially crystals that can produce coherent light in the deep-ultraviolet (DUV) region is essential for the development of diverse fields. Here, we successfully discovered and synthesized a new DUV transparent NLO crystal KMg­(H2O)­PO4 (KMP) using KTiOPO4 (KTP) as a template through substituting TiO6 by the MgO5(H2O) group. Its structure constructed by 2D [MgPO5]∞ infinite layers in which PO4 groups arrange orderly leads to KMP exhibiting a large second harmonic generation (SHG) efficiency (≈1.14 × KDP) which is similar to KBe2BO3F2 (1.2 × KDP). Moreover, the ultraviolet cut-off edge of KMP is blue-shifted to