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

Abstract

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.