All-fiber highly efficient delivery of 2 kW laser over 2.45 km hollow-core fiber

TL;DR

This paper demonstrates an all-fiber system capable of delivering 2 kW of laser power over 2.45 km with high efficiency and stability, utilizing a novel anti-resonant hollow-core fiber with record low loss and suppressed Raman scattering.

Contribution

The work introduces a self-fabricated AR-HCF with record low loss and achieves high-power, long-distance laser delivery in an all-fiber configuration, surpassing previous systems in power-distance product.

Findings

Achieved 85.3% transmission efficiency over 2.45 km

Recorded a low transmission loss of 0.175 dB/km at 1080 nm

Suppressed stimulated Raman scattering in the fiber

Abstract

Anti-resonant hollow-core fibers (AR-HCFs) have emerged as an important medium for high-power laser delivery due to their low optical nonlinearity and high damage threshold. However, current delivery systems of high-power laser based on AR-HCFs mainly rely on free-space optical components, which limits long-term stability in dynamic environments. Here, we report an all-fiber delivery of 2 kW laser with 85.3% transmission efficiency over 2.45 km, using a self-fabricated AR-HCF with a record low transmission loss of 0.175 dB/km at 1080 nm. This represents a nearly 500-fold improvement in the power-distance product compared to reported all-fiber AR-HCF-based laser transmission systems, achieving a record transmission distance for high-power laser delivery. Notably, we observed the phenomenon of stimulated Raman scattering amplified within the silica nested tubes in AR-HCF for the first time. By effectively suppressing the Raman noise from the laser source, we achieve an all-fiber laser delivery without stimulated Raman scattering of silica glass. This work marks a significant breakthrough in multi-kilometer and multi-kilowatt power delivery that is potentially useful for industrial manufacturing, nuclear decommissioning, laser drilling of oil, particle acceleration and so on.