Laser Machining of Micro-Channels in Hollow-Core Optical Fibers for Improved Gas Exchange

Hollow-core optical fibres (HCFs) are a promising platform for diverse applications including telecommunications, laser power delivery, and sensing. To maximize optical performance of HCFs, control of gas composition and pressure within the core is advantageous. Furthermore, HCFs can enable high-sensitivity gas detection through enhancing the gas-light interaction length. Yet, conventional fibre gas filling approaches rely on fibers end filling, which gives an impractically slow response for long lengths as filling time scales quadratically with length [1]. Introducing micro-channels by laser-assisted micro-processing the fibre side allows gas to enter at multiple points [2]. Studies show feasibility in limited fiber designs [3], but for practical deployment further development is required to understand the impact of micro-channel size, shape, and distributions on fiber attenuation and how microstructure geometry and jacket thickness affect the ablation process.