High power continuous-wave mid-infrared laser spectral beam combining via Jigsaw-grating architecture.

Spectral beam combining (SBC) using diffraction gratings offers a compact route to scaling laser power and spectral coverage, yet its development is fundamentally limited by the daunting challenge of fabricating large-aperture, high-quality gratings required for multi-channel systems. Here, we propose a Jigsaw-grating architecture to overcome the geometric limitations and fabrication constraints inherent in conventional dual-grating SBC systems. Guided by numerical analysis of the impacts of jigsaw misalignment and fabrication error on combined beam quality, four mid-infrared optical parametric oscillator lasers (3.1-3.7 μm) with self-developed, robust gratings were successfully combined. Combined laser achieved 50.8 W output power at high grating-combining efficiency up to 92.1% while maintaining high beam quality (Mx2 = 1.76, My2 = 1.46)-ranking among the highest combined powers in this spectral range. The architecture establishes a scalable wavelength-agile platform for high-power lasers across multiple spectral bands.