Acta Chimica Sinica ›› 2022, Vol. 80 ›› Issue (3): 259-264.DOI: 10.6023/A21120585 Previous Articles     Next Articles

Special Issue: 中国科学院青年创新促进会合辑

Article

KAg3Ga8S14: 一种高激光损伤阈值的中远红外非线性光学材料

赵锦旭a,b, 张铭枢a, 陈文发a, 姜小明a, 刘彬文a,*(), 郭国聪a,*()   

  1. a 中国科学院 福建物质结构研究所 结构化学国家重点实验室 福州 350002
    b 上海科技大学 物质科学与技术学院 上海 201210
  • 投稿日期:2021-12-27 发布日期:2022-01-12
  • 通讯作者: 刘彬文, 郭国聪
  • 作者简介:
    庆祝中国科学院青年创新促进会十年华诞.
  • 基金资助:
    国家自然科学基金(22075283); 国家自然科学基金(92161125); 中国科学院青年创新促进会(2021300)

KAg3Ga8S14: An Mid- and Far-infrared Nonlinear Optical Material Exhibiting High Laser-induced Damage Threshold

Jinxu Zhaoa,b, Mingshu Zhanga, Wenfa Chena, Xiaoming Jianga, Binwen Liua(), Guocong Guoa()   

  1. a State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China
    b School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
  • Received:2021-12-27 Published:2022-01-12
  • Contact: Binwen Liu, Guocong Guo
  • About author:
    Dedicated to the 10th anniversary of the Youth Innovation Promotion Association, CAS.
  • Supported by:
    National Natural Science Foundation of China(22075283); National Natural Science Foundation of China(92161125); Youth Innovation Promotion Association of CAS(2021300)

Nonlinear optical (NLO) crystals can produce tunable lasers due to their second-harmonic generation, sum-frequency generation, difference-frequency generation and optical parametric oscillation. The famous oxide-based NLO materials such as KH2PO4 (KDP), β-BaB2O4 (BBO) and LiB3O5 (LBO) are widely used in ultraviolet-visible (UV-Vis) region. Nevertheless, they are not suitable for the mid- and far-infrared region because of the strong absorption there. Currently, commercially available IR NLO materials are rare, such as chalcogenides AgGaS2 (AGS), AgGaSe2 and phosphorus ZnGeP2, which have the advantages of large NLO coefficient and wide transmission range, but they have drawbacks, like low laser- induced damage threshold (LIDT). Discovering NLO crystals that exhibit simultaneously large NLO and high LIDT is a huge challenge. Here, the introducing electropositive alkali metal ionic K+ in chalcopyrite AGS successfully affords a new sulfide KAg3Ga8S14 by high temperature solid state reaction. Its crystal structure adopts a three-dimensional honeycomb-like open framework, in which all tetrahedral AgS4 and GaS4 units are arranged in a highly oriented manner, thereby producing about a medium phase-matching second harmonic generation (SHG) response of 0.4 times that of the benchmark AGS at the incident laser of 1910 nm. Remarkably, the compound possesses a wide band gap (2.95 eV), thus avoiding two-photon absorption of the incident 1064 nm laser, and exhibits a high LIDT of 4.6 times that of the AGS at the laser of 1064 nm. Moreover, KAg3Ga8S14 has a wide transmission range (0.25—25.0 μm) that covers the two important atmospheric windows of 3—5 and 8—12 μm. Furthermore, according to theoretical calculations, the conductive band is mostly composed of Ga-4s and S-3p states, mixing with small amounts of Ga-4p state, whereas the valence band near the Fermi level originates predominately from Ag-4p and S-3p states, mixing with small amounts of Ga-4p state, indicating that tetrahedral GaS4 and AgS4 units govern the optical and NLO properties of chalcopyrite KAg3Ga8S14.

Key words: chalcogenide, nonlinear optical, second harmonic generation, laser damage threshold, crystal structure