Fluoride fibre laser operating at 3.9 µm

Recent Advances in 3.5 μm Erbium-Doped Mid-Infrared Fiber Lasers

“…1 and Fig. 3, together with the results from Braunschweig Group [22] demonstrate that fiber lasers can span the entire 2.6-3.9 µm wavelength range, which covers the important light absorption "fingerprint" range of many Fig. 3.…”

“…It also demonstrates that until recently the output power versus wavelength follows a trend line that decreases exponentially with increasing wavelength until 3 µm, above which the laser power fell significantly to 10 mW. [22] Near−infrared…”

“…1. Published laser power from rare-earth doped fiber laser as a function of operating wavelength [9]- [22]. The trend of reduced power as the wavelength increases (dashed orange line) is mostly a result of the energy difference between pump and laser photons.…”

“…Recent development since 2012 [8] are marked with a blue circle. The Ho 3+ based 3.9 µm laser required cryogenic cooling [22].…”

“…They demonstrated lasers that operated at 3.2 µm [16] and 3.9 µm (cryogenically) [22] using Ho 3+ :ZBLAN fiber and at 3.5 µm [20] using Er 3+ :ZBLAN fiber. These lasers had high threshold and low slope efficiencies, particularly when operated at room temperature.…”