Novel Stress Sensor Using a Fiber Bragg Grating and a Long Fiber Period Grating

Abstract

A novel stress/temperature sensor using fiber Bragg grating and long fiber period grating is shown. The sensor setup was build with a broadband light source made by an erbium fiber doped, pumping at 980 nm, an optic circulator, one fiber Bragg grating (FBG), one long period fiber grating (LPFG) and a photo‐detector. When light from the doped fiber comes to the FBG, this device reflects light centered at λB. The reflected light travels through the circulator to the LPFG. If the spectra of the FBG and LPFG are slight different then it is possible to measure light at end of the LPFG. When a physical variable is applied in the FBG the reflection spectrum is shifted and it could overlap with the transmittance spectrum of the LPFG and in this way to obtain changes in the intensity output. This sensor has the advantage to be cheaper than the conventional one, because it does not use an optical spectrum analyzer (OSA)