10‐W Mid‐Infrared Quantum Cascade Laser Fiber‐Beam‐Combining Source
Kaihang Li, Chuanfei Yao, Lei Ren, Xuan Wang, Linjing Yang, Guochuan Ren, Yamin Liu, Luyao Pu, Kai Jiao, Xunsi Wang, Pingxue LiABSTRACT
Mid‐infrared quantum cascade lasers (QCLs), featuring tunable wavelengths, compact form factors, and high electro‐optical efficiency, are widely used in molecular spectroscopy, biomedical diagnostics, optical communications, and defense. However, the output power of a single QCL is fundamentally limited by thermal effects and device design. Therefore, fiber‐based beam combining provides an effective route for power scaling, offering high efficiency, compact structure, and superior optical‐axis stability compared with polarization, spectral, and spatial combining schemes. Despite these advantages, practical implementation remains challenging. The high refractive index of As 2 S 3 fibers induces strong Fresnel reflections at the fiber end facets, degrading coupling efficiency and destabilizing system stability. Consequently, the power of mid‐infrared QCL fiber‐combining systems has remained limited, with power remaining below 10 W. Here, we demonstrate a high‐power mid‐infrared QCL fiber‐combining system based on a low‐loss As 2 S 3 fiber combiner. A self‐developed liquid glass is introduced for refractive index matching, effectively suppressing Fresnel reflections and improving both coupling efficiency and operational stability. The system achieves a maximum output power of 10.361 W with a transmission efficiency of 73%, representing the first demonstration of a mid‐infrared QCL fiber‐combining system exceeding 10 W and providing a promising route for high‐power mid‐infrared laser generation.