Watt-level erbium-doped all-fiber laser at 344  μm

Abstract

We demonstrate a 3.44 μm all-fiber laser emitting a maximum of 1.5 W at room temperature, the highest continuous power ever generated from a mid-IR fiber oscillator clearly beyond 3 μm. The laser operates on the 4F(9/2)→4I(9/2) transition of erbium-doped fluoride glasses and relies on a dual pumping scheme at 974 and 1976 nm. By combining a dichroic mirror deposited on the input fiber tip and a fiber Bragg grating as an output coupler, a stable laser emission is produced with a FWHM bandwidth of less than 0.6 nm. The laser cavity has an efficiency of 19% with respect to the launched pump power at 1976 nm and no saturation is observed provided 974 nm co-pumping is sufficient. The joint effect of the two pumps is also investigated.

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

“…1. Further power scaling to 1.5 W output power was demonstrated recently by our group [19] and the Université Laval group [18] who used an all fiber approach.…”

Versatile and widely tunable mid-infrared erbium doped ZBLAN fiber laser

“…The functional group region of the mid-infrared can now be accessed using moderate power and, potentially, high power fiber laser sources, opening up the opportunity for the development of high brightness pump sources for applications in mid-infrared nonlinear optics and high peak power mid-infrared lasers. The recent report [10] of 1.5 W at a wavelength of 3.44 μm demonstrates the power scaling capability of the concept.…”

“…However, the laser could not sustain this power level and would cease operation after a few minutes due to the damage to the fiber core. The use of fiber end-capping [10] would alleviate this issue. During operation with P 2 at lower power levels of 2 and 3 W, some residual 2.8 μm lasing (5 and 2 mW, respectively) was observed.…”

“…At this power level, the laser output suffered from strong instabilities, possibly, due to thermal and mechanical stress at the fiber pump input facet which prevented additional pump power from increasing the laser power further. It is clear that the recent demonstration [10] that employs fiber post-processing to avoid large intensities at the glass-air boundary is necessary at elevated power levels. The laser operated on a number of lines in the 3.45-3.47 μm region with the distribution of power shifting to the longer lines with increasing pump power (Fig.…”

New energy-transfer upconversion process in Er^3+:ZBLAN mid-infrared fiber lasers

“…We reported a continuous-wave (CW) output power in excess of 250 mW which was the first room temperature rare-earth doped fiber laser to produce more than 10 mW well beyond 3 µm [2]. Recently two groups have reported over 1 W of power at 3.5 µm using this approach [3,4]. In this paper we report a new energy-transfer (ET) process that must be considered for the successful optimization of lasers that operate on the 3.5 µm transition in erbium using low phonon energy hosts.…”