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Updated: Sep 18, 2025

Hyperspectral Imaging as a Tool to Study Optical Anisotropy in Lanthanide-Based Molecular Single Crystals
Published on: April 14, 2020
Nonlinear Optical Series A(VO2)3(SeO3)2 (A = NH4+, K+, and H3O+) with Large Birefringence Derived from
Qian Wu1, Tianyu Wang1,2, Jingfang Zhou3
1Beijing Center for Crystal Research and Development, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
Abstract:
With the increasing significance of the laser industry, especially in the 3-5 μm range, mid-infrared (mid-IR) nonlinear optical (NLO) crystals have become crucial components to meet stringent requirements. Herein, a large birefringence is essential for a mid-IR NLO crystal, as it ensures the phase-matching condition for high-conversion efficiency in laser output operation. In this study, three vanadium selenites A(VO2)3(SeO3)2 (A = NH4+, K+, and H3O+) with hexagonal tungsten oxide-related structures were prepared, featuring two-dimensional layered structures composed of two second-order Jahn-Teller (SOJT) motifs: distorted VO6 octahedra and SeO3 pyramids. Owing to the highly anisotropic VO6 octahedra and SeO3 pyramids, the family of A(VO2)3(SeO3)2 (A = NH4+, K+, and H3O+) crystals shows significant birefringence, which represents the highest birefringence value among vanadium selenites, even surpassing some SOJT-cation-based oxides. In addition, the title crystals exhibit large second harmonic generation responses of powder of 0.28-0.58 × AgGaS2 (AGS) at 2.09 μm.
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