2.2 kW single-mode narrow-linewidth laser delivery through a hollow-core fiber

Antiresonant hollow-core fibers (AR-HCFs) have opened up exciting possibilities for high-energy and high-power laser delivery because of their exceptionally low nonlinearities and high damage thresholds. While these fiber designs offer great potential for handling kilowatt-class powers, it is crucial to investigate their performance at multi-kW power levels. Until now, transmission of narrow-linewidth single-mode lasers at multi-kW power levels through a HCF has not been demonstrated, to our knowledge. Here, we present the delivery of a record 2.2 kW laser power with an input spectral linewidth of 86 GHz, centered at 1080 nm, while maintaining 95% transmission efficiency and beam quality (M2) of 1.03. This was achieved via a 104.5 m single-mode five-tube nested AR-HCF with 0.79 dB/km loss. Furthermore, we show power delivery of 1.7 kW with a spectral linewidth as narrow as 38 GHz through the same fiber. Our results could lead to a new generation of fiber-based laser beam delivery systems with applications in precision machining, nonlinear science, directed energy, and power beaming over fiber. (c) 2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement