In this Letter, we report a compact and robust coherent source, operating in mid-infrared (IR) and based on the Fe:ZnSe chalcogenide gain medium, optically pumped by an Er:ZBLAN fiber laser. The output power of 2.1 W with a 59% slope efficiency with respect to the absorbed pump power at liquid nitrogen cooling is achieved. We show that strong re-absorption at a high pump power and iron ion doping concentrations leads to a continuous tuning of central wavelength from 4012 to 4198 nm. The robustness of a high-power Er:ZBLAN fiber laser combined with prominent spectroscopic properties of Fe:ZnSe media pave the way for the development of a reliable tunable continuous-wave mid-IR sources for scientific and industrial purposes.

A fluoride-fiber-based master oscillator power amplifier (MOPA) for 30-W class continuous-wave (cw) operation at 2.8-μm wavelength has been demonstrated. To overcome the low durability of ZBLAN fibers, various novel technologies for using fluoride glass with a ZBLAN-fiber-based side-pump combiner have been adopted in the system. A maximum cw output power of 33 W and stable operation under 23-W output have been demonstrated. We suggest that such fiber MOPA systems will open up advanced fluoride fiber technology for next-generation high-power mid-IR lasers.

We report the femtosecond laser inscription of fiber Bragg gratings (FBGs) in an Er-doped fluoride glass fiber used for lasing at a mid-infrared wavelength of 2.8 µm. The lasing evolution is discussed in terms of the FBG reflectivity, wavelength transition to the Bragg wavelength, and output power of the mid-infrared fiber laser. A first-order and short (2.5-mm-long) Bragg grating showed a reflectivity of 97%, because of a laser-induced index modulation of 1.1 × 10⁻³. This modulation was sufficient to saturate this system’s output power. The laser oscillator is designed to lase in the atmospheric window of 2799–2800 nm slope. Further, this oscillator’s efficiency is as high as 29.1% for the launched pump power over the range of 0.4–4.6 W and at a lasing wavelength of 2799.7 nm. This oscillator also exhibited a FWHM bandwidth of 0.12 nm.

An actively Q -switched mid-infrared Fe:ZnSe laser pumped by a continuous wave fluoride fiber laser has been developed. Stable operation with a pulse duration of 20 ns and a repetition rate of 40 kHz at 4 µm was achieved. The maximum peak power was 1.1 kW. The high-repetition rate, high-peak power nanosecond pulsed laser, which has been created for the first time, to the best of our knowledge, in an actively Q -switched Fe:ZnSe laser, should prove a suitable light source for laser processing and molecular sensing.