From Ce(IO3)(4) to CeF2(IO3)(2): fluorinated homovalent substitution simultaneously enhances SHG response and bandgap for mid-infrared nonlinear optics

Abstract

Efficient mid-infrared (mid-IR) nonlinear optical (NLO) crystals are highly desirable, but it remains extremely challenging to simultaneously achieve a strong second harmonic generation (SHG) response, a large optical bandgap, and wide optical transparency in a material. In this work, a fluorinated homovalent substitution strategy has been put forward and this strategy leads to a new cerium fluorinated iodate, CeF2(IO3)(2), which is designed based on a noncentrosymmetric cerium iodate, Ce(IO3)(4). The introduction of F- ions enables CeF2(IO3)(2) to achieve the simultaneous enhancement of an enlarged phase-matchable SHG response that is 8 times that of KH2PO4 (KDP) and a bandgap of 2.90 eV compared to its parent Ce(IO3)(4) (0.9x KDP and 2.17 eV, respectively). CeF2(IO3)(2) exhibits a high thermal stability (similar to 430 degrees C) and a wide transparent region (0.43-6.46 mu m), suggesting that CeF2(IO3)(2) is a promising mid-IR NLO material. First-principles simulations reveal that the difference in linear and nonlinear optical properties between Ce(IO3)(4) and CeF2(IO3)(2) is mainly attributed to the divergent anisotropies of the cerium-centered polyhedra. Show more