Fig. 1. Properties of the EYDSF. (a) Distribution of the refractive index difference. (b) The absorption spectrum. (c) The excitation-emission spectra. (d) The fluorescence decay curves.

Fig. 2. Gain coefficients, unsaturated absorption, and laser output power with different pump wavelengths. (a) Gain coefficients as a function of the pump powers. (b) Unsaturated absorptions of 980 and 1480 nm pumps. (c) Output power of the DBR laser as a function of the pump power (the difference between the input pump power and the residual pump power) at different pump wavelengths without the mirror.

Fig. 3. Experimental setup. (a) The fiber laser system. (b) The transmission spectra of the FBG pairs. (c) Calculation of SLM conditions.

Fig. 4. Longitudinal modes and linewidth characteristics of the DBR fiber laser. (a) Radio frequency beating intensities of the fiber laser at different pump powers. (b) The heterodyne signal of the fiber laser with a pump power of 565 mW.

Fig. 5. Properties of the LP-DBR fiber laser. (a) Slope efficiency of the fiber laser with and without fiber mirror. (b) The output spectrum of the lasing under the maximum output power, and the inset is a zoomed-in view near the laser peak.

Fig. 6. Polarization state of the laser. (a) Output power of the different angles of the polarizer. (b) The stability of the PER at different pump powers.

Fig. 7. (a) Relative intensity noise (RIN) (the inset shows the laser output power dependences on time measured by an oscilloscope). (b) Laser power stability recorded within 2 h at 103 mW (the inset shows the power recorded in half an hour).