Multi-watt QCW operation of Fe:ZnSe laser at 4.1 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si5.svg" display="inline" id="d1e193"> <mml:mi mathvariant="normal">μ</mml:mi> </mml:math> m

This study reports on the realisation of multi-watt QCW laser operation of a Fe:ZnSe laser under cryogenic conditions at 77 K. The Fe:ZnSe gain medium was longitudinally pumped by a high-power, compact diode-pumped solid-state (DPSS) Er:YAG laser emitting at 2.94 μ m. The resulting laser system, characterized by its compact and efficient design, achieved an output power of up to 16.3 W at 4.1 μ m with a maximum slope efficiency of 45% with respect to incident power. These results highlight the feasibility and strong potential of Fe:ZnSe lasers for high-power mid-infrared applications, particularly in contexts where compactness, efficiency, and cryogenic operation are practical or advantageous. • Compact Fe:ZnSe laser system with a single DPSS Er:YAG pump and compact cryogenic cooling delivers 0.1 J pulse energy at 4.1 μ m. • Output powers up to 16.3 W at 4.1 μ m were achieved with a high slope efficiency of 45%, demonstrating excellent energy conversion. • Long-term stable QCW operation at 10 W suggests suitability for practical mid-IR applications.