Low cost optical fibre based Fabry–Perot strain sensor production

Abstract

The production of Fabry-Pérot based optical fibre sensors has long been an iterative\nand labour intensive process. This paper demonstrates the production of Fabry-Pérot\nbased optical fibre strain sensors using chemical etching techniques. Utilising\nhydrofluoric acid (HF) and singlemode optical fibres, a preferential etching\nmechanism was observed around the core portion of the fibres. These etched fibre\nends were then spliced together successfully to form enclosed Fabry-Pérot cavities\nbetween 18 and 60 μm in length. These sensors have then been deployed for strain\nmonitoring and have been subjected to strains of up to 1400 με on tensile test\nspecimens. Etched Fabry-Pérot cavity lengths were monitored using a white light\ninterferometry (WLI) system based on a CCD spectrometer and an 850 nm super\nluminescent diode (SLD). A linear and repeatable response to these strain tests has\nbeen shown with negligible sensitivity to temperature.