硼酸钙镧晶体是一种激光基质晶体, 以其优秀的物理特性而受到广泛关注。稀土离子掺杂的硼酸钙镧晶体在紫外激光器领域的研究尚不多见。本研究采用顶部籽晶法成功生长出尺寸为40 mm×21 mm×6 mm的铈掺杂硼酸钙镧晶体。研究了铈掺杂硼酸钙镧晶体室温光谱性质, 测量了室温下其透过光谱以及紫外-吸收光谱, 发现铈离子掺杂导致晶体在200~288 nm以及305~330 nm紫外波段吸收较强。测试了室温下铈掺杂硼酸钙镧晶体的激发光谱, 并且利用波长260 nm的连续光激发得到发射光谱, 发现主要发射带中心波长位于290, 304, 331和353 nm处, 对应于铈离子5d态到²F_5/2和²F_7/2态的跃迁。对铈掺杂硼酸钙镧晶体的热学性质进行了研究, 发现其在300 K下具有较高的热导率(6.45 W/(m·K)), 且随着温度升高保持良好的热稳定性。358 K条件下, 热膨胀系数及c方向的晶格常数分别为2.94×10^-6 /K和0.91240 nm, 随着温度升高至773 K，线性增加到5.3×10^-5 /K和0.91246 nm。研究结果表明：铈掺杂硼酸钙镧晶体具有良好的光学性能和热稳定性, 适合应用于紫外激光领域。

ZnGeP₂ (ZGP) crystals have attracted tremendous attention for their applications as frequency conversion devices. Nevertheless, the existence of native point defects, including at the surface and in the bulk, lowers their laser-induced damage threshold by increasing their absorption and forming starting points of the damage, limiting their applications. Here, native point defects in a ZGP crystal are fully studied by the combination of high angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and optical measurements. The atomic structures of the native point defects of the Zn vacancy, P vacancy, and Ge-Zn antisite were directly obtained through an HAADF-STEM, and proved by photoluminescence (PL) spectra at 77 K. The carrier dynamics of these defects are further studied by ultrafast pump-probe spectroscopy, and the decay lifetimes of 180.49, 346.73, and 322.82 ps are attributed to the donor V_p⁺ → valence band maximum (VBM) recombination, donor Ge_Zn⁺ → VBM recombination, and donor–acceptor pair recombination of V_p⁺ → V_Zn^-, respectively, which further confirms the assignment of the electron transitions. The diagrams for the energy bands and excited electron dynamics are established based on these ultrahigh spatial and temporal results. Our work is helpful for understanding the interaction mechanism between a ZGP crystal and ultrafast laser, doing good to the ZGP crystal growth and device fabrication.

ErxY2?xSiO5 and ErxYbyY2?x?ySiO5 crystalline thin films were investigated to apply to the high-gain media for silicon photonics. In addition to the sol–gel method, the directed self-assembly approach, using layer-by-layer deposition techniques, was also introduced to improve the crystallinity. The relaxation processes in Er ions were discussed to clarify the contribution of the energy transfer and cooperative upconversion. After optimization of the Er content, a Si photonic crystal slot ErxY2?xSiO5 waveguide amplifier was fabricated, and a 30dB/cm modal gain was demonstrated. This achievement demonstrates the potential for compact and high optical gain devices on Si chips.