Inorganic Solid‐State Nonlinear Optical Switch with a Linearly TunableTcSpanning a Wide Temperature Range

Abstract

AbstractNonlinear optical (NLO) switch materials that turn on/off second‐harmonic generation (SHG) at a phase transition temperature (Tc) are promising for applications in the fields of photoswitching and optical computing. However, precise control ofTcremains challenging, mainly because a linearly tunableTchas not been reported to date. Herein, we report a unique selenate, tetragonalP21c[Ag(NH3)2]2SeO4witha=b=8.5569(2) Å andc=6.5208(2) Å that exhibits a strong SHG intensity (1.3×KDP) and a large birefringence (Δnobv.=0.08). This compound forms a series of isostructural solid‐solution crystals [Ag(NH3)2]2SxSe1−xO4(x=0–1.00) that exhibit excellent NLO switching performance and an unprecedented linearly tunablespanning 430 to 356 K. The breaking of localized hydrogen bonds between SeO42−and the cation triggers a phase transition accompanied by hydrogen bond length changes with increasingxand a linear change in the enthalpy.