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Updated: Sep 30, 2025
20 mJ, 1 ps Yb:YAG Thin-disk Regenerative Amplifier
Published on: July 12, 2017
Ultrawide Bandgap and Outstanding Second-Harmonic Generation Response by a Fluorine-Enrichment Strategy at a
Tianhui Wu1, Xingxing Jiang2, Chao Wu1
1China-Australia Joint Research Center for Functional Molecular Materials, School of Chemical Science and Engineering, Tongji University, Shanghai, 200092, China.
Abstract:
The development of nonlinear optical (NLO) materials has been hindered by competing microstructure requirements: the need to simultaneously engineer a large hyperpolarizability (a large second-harmonic generation (SHG)) and a wide HOMO-LUMO gap (a wide band gap). Herein, a non-centrosymmetric transition-metal (TM) oxyfluoride K5 (NbOF4 )(NbF7 )2 (KNOF) with an extremely high F/O ratio is constructed in high yield. KNOF exhibits an extremely wide band gap (5.88 eV) and a strong powder SHG response (4.0×KH2 PO4 )-both being the largest values for TM-centered oxyfluorides-as well as a birefringence sufficient for applications. The dominant roles of the partially fluorinated [NbO2 F4 ] and totally fluorinated [NbF7 ] groups in achieving the enlarged band gap in KNOF have been clarified by first-principles calculations. Our results suggest that maximizing the fluorine content of oxyfluorides may unlock the promise of short-wavelength-transparent materials with exceptional NLO performance.
