Fig. 1. Schematic diagrams for experimental setups. (a) Dual-end-pumped Er∶CaF₂ laser; (b) wavelength tunable Er∶CaF₂ laser

Fig. 2.

Variation of single-end-pumped and dual-end-pumped Er∶CaF₂ CW lasers output power with the pump power, where insert (a) is power meter reading and insert (b) is beam quality factor M² at the output power of 5.04 W

Fig. 3. Laser spectra of a dual-end-pumped Er∶CaF₂ laser at different output powers and emission spectrum of Er∶CaF₂ crystals with doping concentration of 2%

Fig. 4.

Comparison of the LD-end-pumped erbium-doped fluoride crystal lasers CW output power^{[13,18-19,22-42]}

Fig. 5. Tunable spectra and output power curves of Er∶CaF₂ lasers corresponding to BRFs with different thicknesses. (a) d=1 mm; (b) d=2 mm; (c) d=4 mm