Optical fibre Fabry-Pérot sensor stability at high temperatures

In this paper we present long-term stability results for a Fabry-Pérot optical fibre sensor in high temperatures environments. We introduce an intrinsic Fabry-Pérot type of sensor, which its sensing element is made with an undoped pure fused silica cavity. Furthermore, we will present results detailing dopant diffusion from core to cladding of standard optical fibres demonstrating their inherent unsuitability for high temperature environments. Finally, we display the manufacturing technique required to produce this sensor and we present results of 33 days long stability tests conducted at elevated temperatures of more than 900°C.