All-Silicon Packaging Technology for Fiber Bragg Gratings and Its Application in Tilt Sensor

Abstract

A fiber Bragg grating (FBG) sensor includes three main parts, an FBG, a sensor substrate, and a packaging material. The most commonly used packaging material is epoxy resin adhesive, which is prone to aging and failure, which further affects the performance and life of a sensor. This research provides an innovative approach that enables all-silicon sensor fabrication, where the substrate and packaging material are prepared by silicon glass, which is consistent with silicon optical fiber. In the packaging process, there are three main bottleneck problems, which are considered in this study: 1) highly elastic processing of glass used in the sensor elastic element; 2) thermal fixation between the silicon packaging material and substrate; and 3) selecting appropriate FBG parameters and fixing methods. In the proposed approach, an elastic glass cantilever beam and an FBG are packaged with molten glass powder. The proposed approach is verified by tests, and the test results show that the packaged FBG has good package quality and sensing performance. The theoretical analysis of the wavelength drift phenomenon during the packaging is presented. Finally, the introduced packaging method is applied to the fabrication of an FBG tilt sensor. The sensor shell, cantilever beam, temperature compensation beam, mass block, and other components are designed and made of silicon glass. The sensing principle and performance tests of the tilt sensor have been described in detail. The tilt sensor shows good linearity and repeatability. The presented packaging technology shows good applicability and has promising applications in the fabrication of high-performance FBG sensors.