Widely Wavelength-Tunable Mid-Infrared Fluoride Fiber Lasers

We demonstrate widely wavelength-tunable continuous-wave (CW) and Q-switched Er
³⁺
-doped ZBLAN fluoride fiber lasers operating around 3 μm enabled by a volume Bragg grating (VBG). In the CW operation regime, a total wavelength tuning range of over 160-nm spanning from 2694 to 2854 nm has been achieved. For the Q-switched mode of operation, a slightly modified resonator configuration, incorporating a passive Q-switcher, topological insulator Bi
₂
Te
₃
nanosheets, can produce stable pulse trains with a pulse width of 880 ns at a repetition rate of 81 kHz, while maintaining a wavelength tuning range of 62 nm from 2762 to 2824 nm through adjusting the VBG. In both operation regimes, the output spectral width is measured to be <;0.3 nm (full-width at half-maximum) over the whole tuning range. Our work both demonstrates the great wavelength-tuning potential of the Er
³⁺
-doped fluoride fiber laser, and also paves a way for the development of a range of high-performance midinfrared laser sources.