Packaging a fiber Bragg grating without preloading in a simple athermal bimaterial device

This study presents two athermal packages for compensating for the temperature deviations in an optical fiber Bragg grating (FBG). Usually, a pre-loading mechanism is necessary in packaging the FBG on bimaterial devices. However, through a unique bonding process design, the pre-loading mechanism in the packaging could be eliminated. During the manufacturing processes, AB thermally cured adhesive is used to affix the FBG to the device under a thermal state. In this way, the FBG affixed to the devices is under tension when the temperature drops to room temperature. The devices can also be placed continuously under a thermal state after a thermal curing process for a pre-determined period of time to perform annealing on the FBG, and thereby, further simplifying the manufacturing process. As a result, the total variation in the Bragg wavelength over the range from -40 to +80°C was around 0.1 nm in the two proposed athermal packages