F₂-laser ablation of Fabry-Perot cavities in optical fibres : chemical sensors

The authors have previously reported on the micro-machining of intrinsic fibre Fabry-Perot cavities in fused silica optical fibres using a 157 nm excimer laser. The current paper reports on a technique for estimating the depth of the cavity by measuring the transmitted light intensity during the micro-machining of optical fibres using a 157 nm laser. Single and multiple cavities were created in silica and sapphire optical fibres and the feasibility of using micro-machined cavities for monitoring chemicals is demonstrated.