Fig. 1. Characteristics of the Yb∶YAG crystal-derived fiber. (a) Composition distribution of the Yb∶YAG crystal derived silica fiber (YDSF), the insert is the optical micrograph of the fiber cross-section; (b) refractive index of the fiber; (c) absorption and emission spectra of the fiber; (d) transmission loss at 1550 nm measured by cut-back method

Fig. 2. Gain characteristics of the Yb∶YAG crystal-derived fiber at 976 nm. (a) The schematic of the amplifier setup based on the YDSF; the dependence of the gain coefficient of the YDSF on the pump power at (b) 1-cm YDSF and (c) 2-cm YDSF, the inserts are the signal output spectra of the amplifier at 181 mW pump power

Fig. 3. Laser characteristics of 976-nm Yb∶YAG crystal-derived fiber laser. (a) The schematic of the fiber laser at 976 nm; the dependence of output power on the launched pump power with (b) various fiber lengths and (c) various reflectivities of 976 nm laser (L_YDSF=1 cm)

Fig. 4. Linearly polarized single-frequency YDSF laser at 976 nm

Fig. 5. Laser characteristics of 976-nm single-frequency fiber laser. (a) Output power of the fiber laser with respect to the launched pump power; (b) output spectrum of the fiber laser from 900 nm to 1100 nm, the insert is the laser spectrum measured in 0.02 nm resolution; (c) beam quality of the single-frequency laser, the inset is the two-dimensional beam profile of the fiber laser

Fig. 6. Longitudinal mode and linewidth characteristics of 976 nm single-frequency fiber laser. (a) Longitudinal mode characteristics of the fiber laser measured by the scanning Fabry-Perot interferometer; (b) measured self-heterodyne signal of the single-frequency fiber laser with the Lorentzian fitted linewidth