Ultrahigh temperature and strain hybrid integrated sensor system based on Raman and femtosecond FBG inscription in a multimode gold-coated fiber

In this paper, a novel approach for hybrid systems combining Raman distributed sensors with fiber Bragg grating (FBG) sensors to carry out distributed and quasi-distributed temperature/strain measurements was proposed and experimentally demonstrated. Three FBGs were inscribed by the point-by-point technique in a simple setup for type I femtosecond inscription in a pure silica core multimode gold-coated fiber. Employing a single fiber, temperatures up to 600 degrees C and strains up to 4144 mu epsilon approximately were measured simultaneously and without interferences between both distributed and point measurements. Moreover, a new calibration technique was implemented to calibrate the distributed temperature system using the FBG measurements as reference. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement