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A Photonic System for Generating Unconditional Polarization-Entangled Photons Based on Multiple Quantum Interference
Published on: September 5, 2019
An Ultraviolet Transparent Nonlinear Optical Crystal Assembled from a Polarizable Tetrahedral Unit
Ning Yang1,2, Li Shen2, Zhiyong Bai3
1Key Laboratory of Modern Precision Measurement and Laser Nondestructive Testing of Fujian Province, Putian University, Putian, Fujian 351100, China.
None:
Polarizable tetrahedra consisting of two distinct types of chemical bonds are of great interest in the design of nonlinear optical (NLO) crystals that are transparent in the ultraviolet (UV) and deep-UV regimes. Herein we report a hydrated barium methylsulfonate, Ba2(CH3SO3)4·3H2O, that crystallizes in the noncentrosymmetric space group Pna21. Its crystal structure adopts a quasi-two-dimensional framework built from [BaO7]/[BaO8] polyhedra and polarizable [CH3SO3]- tetrahedra. Centimeter-sized single crystals were obtained by using a facile solution-evaporation method. Optical measurements show that the title compound is UV-transparent with a short cutoff edge at 207 nm. It exhibits phase-matchable second-harmonic generation (SHG) in the visible region, with a moderate efficiency of 0.6 times that of KDP, and shows a birefringence value of 0.012 at 550 nm. First-principles calculations reveal that its optical properties originate mainly from the [CH3SO3]- groups as well as H2O molecules.
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