物理化学学报 >> 2020, Vol. 36 >> Issue (1): 1907009.doi: 10.3866/PKU.WHXB201907009

所属专题: 庆祝唐有祺院士百岁华诞专刊

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硅酸镓镧族非线性光学晶体

王继扬*(),路大治,于浩海,张怀金   

  • 收稿日期:2019-07-01 录用日期:2019-08-02 发布日期:2019-08-29
  • 通讯作者: 王继扬 E-mail:jywang@sdu.edu.cn
  • 作者简介:王继扬,山东大学国防科技委主任、教授。1968年毕业于南京大学化学系,现任国家973计划领域专家咨询组成员,国际晶体生长组织理事,亚洲晶体生长与晶体技术协会执委,中国晶体生长协会副理事长兼秘书长,中国晶体学会晶体生长与表征分会理事长,山东省硅酸盐学会理事长。长期从事功能晶体生长及其应用研究,潜心发展晶体生长技术,致力于晶体特性研究和应用开拓,成功生长30余种单晶,多种晶体获得应用及产业化
  • 基金资助:
    国家自然科学基金(51772172)

Langasite Family Nonlinear Optical Crystals

Jiyang Wang*(),Dazhi Lu,Haohai Yu,Huaijin Zhang   

  • Received:2019-07-01 Accepted:2019-08-02 Published:2019-08-29
  • Contact: Jiyang Wang E-mail:jywang@sdu.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(51772172)

摘要:

中红外非线性光学晶体可以实现中红外激光频率转换、拓展激光波长,在民用和军用领域中有至关重要的应用价值。其中,硅酸镓镧族晶体具有透过范围宽、激光损伤阈值高、晶体质量好等优势,引起了国内外同行的广泛关注。在这篇综述中,我们基于现有的实验数据,研究和分析了三种重要的硅酸镓镧族晶体La3Ga5SiO14 (LGS)、La3Ga5.5Nb0.5O14 (LGN)、La3Ga5.5Ta0.5O14 (LGT)的综合性能,详细总结了它们在电光调Q开关和中红外光参量振荡以及差频激光输出方面的应用。最后,本文还讨论了今后硅酸镓镧族中红外非线性光学晶体的重点发展方向。

关键词: 硅酸镓镧族, 中红外, 电光, 非线性, 光参量振荡

Abstract:

In the 1960s, Maiman constructed the first laser. Pulsed lasers with high repetition rates and short pulse widths have extensive applications in fiber optics, military applications, spectroscopy, laser ranging, materials processing, medicine, and frequency conversion, etc. For instance, short pulse lasers with high repetition rates are desirable for material processing, in which the processing speed depends upon the repetition rate of the laser source. Electro-optic Q-switching has numerous advantages in many fields because of its better hold-off ability, larger pulse energy, and more controllable repetition rates. In 1961, Franken et al. first applied a ruby laser directly to quartz crystals and observed double-frequency radiation. Afterward, Bloembergen et al. analyzed the principle of nonlinear optical parametric generation theoretically. Since then, nonlinear optics has been playing an increasingly vital role in human society. Mid-infrared (mid-IR) lasers using nonlinear optical (NLO) crystals have essential applications in science as well as in daily life (e.g., infrared remote sensing, biological tissue imaging, environmental monitoring, and minimally invasive medical surgery). For generating mid-IR lasers in the spectral range of 3–20 µm, NLO materials are indispensable for optical parametric oscillation (OPO) or difference frequency generation. It is common for the available wavelength range to be limited by multiphonon absorption in the oxide crystal, and the damage threshold for semiconductors is relatively low. At present, the most widely used NLO crystal materials in the mid-IR band are semiconductor crystals represented by ZnGeP2. However, their laser damage thresholds are low, which limits their application range. Therefore, one of the key issues in the field of NLO materials at present is to explore new mid-IR NLO crystal materials with excellent performance that are applicable to high-power lasers. Langasite materials are famous for their multifunctionality in optoelectronic applications, such as in piezoelectric convertors, electro-optic Q-switched laser generation, and surface acoustic wave devices. Their structure without central symmetry endows the crystal with electro-optic, piezoelectric, and NLO properties, and their laser damage threshold is high because they are oxides. The phonon energy of the crystal is low and the transmission range is wide owing to their composition, which may have important applications for mid-IR high-power lasers. The Langasite family comprise a set of perfect electro-optical crystals with an electro-optical coefficient of 2.3 × 10−12 m∙V−1, a broad transmission spectral range, and a high optical damage threshold of 950 MW∙cm−2. Besides, their small piezoelectric coefficient (6 × 10−12 C∙N−1) reveals the possibility for Q-switching under high repetition rates without a piezoelectric ring effect. In this brief review, three important compounds—La3Ga5SiO14, La3Ga5.5Nb0.5O14, and La3Ga5.5Ta0.5O14—are investigated and analyzed based on available experimental data. The electro-optical Q-switch and mid-IR OPO applications are summarized in detail. Finally, promising search directions for new metal oxides that have good mid-IR NLO performances are discussed.

Key words: Langasite, Mid-infrared, Electro-optical, Nonlinear, Optical parametric oscillation

MSC2000: 

  • O649