Improvements in the fabrication of microstructured fiber Bragg grating sensors

Abstract

In this work, we propose a novel fabrication method as technological assessment for the development of microstructured fiber Bragg gratings (FBGs) tailorable for specific applications. Micro-structured FBG (MSFBG) relies on the localized stripping of the cladding layer in a well defined region in the middle of the grating structure leading to the formation of a defect state in the spectral response. The key feature of this class of devices is the strong dependence of the defect state generated in the grating spectrum on the optical properties of the medium surrounding the device. In fact, this property enables the development of tunable devices as well as in fiber refractometers and chemical sensors. One of the main drawbacks of these devices is the fabrication process requiring a well precise control of the stripped region dimensions. Here, we demonstrate that the optimization of this device is possible by adopting a fabrication process based on polymeric coatings and UV laser micromachining. These method combined with wet chemical etching allows the easy prototyping of MSFBGs with the desired features for specific applications.