Nd<sup>3+</sup>-doped silica glass and fiber prepared by modified sol-gel method

Yinggang Chen; Zhiquan Lin; Yafei Wang; Meng Wang; Lei Zhang; Yan Jiao; Hehe Dong; Shikai Wang; Chunlei Yu; Lili Hu

doi:10.3788/COL202220.091601

${Nd}^{3 +}$ -doped silica fiber (NDF) has good thermo-mechanical properties of silica glass and a perfect energy level structure of ${Nd}^{3 +}$ ions, which is widely used in communication, biomedical, military, material processing, high-power laser, and other fields^[1,2]. The ${{}^{4}F}_{3 / 2} \to {{}^{4}I}_{11 / 2}$ transition of ${Nd}^{3 +}$ can generate a $\sim 1060 nm$ laser with extremely low laser threshold and long fluorescence lifetime, which benefits the laser output and energy storage. ${Nd}^{3 +}$ -doped glass, crystal, and ceramics are well developed for this band^[3–5]. Moreover, the application of ${Nd}^{3 +}$ in several other bands has also been widely considered by researchers. The ${{}^{4}F}_{3 / 2} \to {{}^{4}I}_{9 / 2}$ transition of NDF can generate a $\sim 900 nm$ laser, which can be directly used in atmospheric detection, lidar, and ${Yb}^{3 +}$ ion pumping^[6]. The deep blue lasers produced by its frequency doubling can be used in underwater communication, precision optics, atom cooling, and other fields^[7,8]. The ${{}^{4}F}_{3 / 2} \to {{}^{4}I}_{13 / 2}$ transition of NDF can generate lasers in the E-band of wavelengths (1350–1450 nm), which plays an important role in the fields of remote sensing, surgery, optical fiber communication, information storage, and so on^[9,10]. These new applications require NDFs with a larger core-to-clad ratio and higher doping concentrations.