Fig. 1. (a) Energy-level schematic of Dy3+; (b) absorption spectrum of 2000 ppm Dy3+-doped ZBLAN fiber (inset, zoom-in absorption spectrum in a range of 410–490 nm); and (c) fluorescence emission spectrum of 3.9-m Dy3+-doped ZBLAN fiber pumped at 450 nm.

Fig. 2. (a) Schematic and (b) photograph of the proposed yellow Dy3+-doped fiber laser; (c) optical transmission spectra of the yellow-reflection mirror (M1) and the fiber end-facet mirror (M2), respectively [insets, photo (left) and microscopic image (right) of the M2].

Fig. 3. Characteristics of yellow fiber laser with a 1.8-m Dy3+-doped ZBLAN fiber. (a) The output power as a function of the pump power; and (b) the optical spectra under different pump powers; (c) the beam quality parameter and near-field intensity distribution of the output laser beam; (d) the central wavelength versus the pump power, and laser power stability measurement.

Fig. 4. Characteristics of yellow Dy3+-doped ZBLAN fiber laser with different output couplings. (a) The output power versus the pump power; and (b) the optical spectra of the yellow fiber laser with different output couplings pumped at 1.50 W.

Fig. 5. Characteristics of yellow fiber laser with different lengths of Dy3+-doped ZBLAN fiber. (a) The output power as a function of the pump power; and (b) the optical spectra of the 0.9, 1.8, and 3.9-m fiber laser pumped at 2.25 W.