Force and temperature characteristics of a fs-laser machined locally micro-structured FBG

A locally micro-structured fiber Bragg grating (LMFBG) was manufactured by forming a circumferential groove in the middle of a type I fiber Bragg grating (FBG). The groove was directly ablated using a fs-laser and had a length of 86 mu m, a depth of 27 mu m and steep side walls. Due to the precisely machined geometry of the structure the reflection spectra can be accurately described with a fairly simple theoretical model. At several constant temperatures in the range from 5 degrees C to 45 degrees C this structure was exposed to various compressive loads in the range from ON to-1.42N. Here the force and temperature sensitivity of the LMFBG are presented. This structure can be used for miniaturized compressive force sensing at variable temperatures, which is of particular interest for many bio-medical applications.