Method for enhancing temperature sensitivity of fiber Bragg gratings based on bimetallic sheets

We designed what is believed to be a novel structure based on bimetallic sheets to enhance temperature sensitivity of fiber Bragg gratings. The two ends of bimetallic sheets were fixed by bolts, and a fiber Bragg grating was longitudinally affixed to one of the sheets whose expansion coefficient was larger than that of the other. The theoretical and experimental results show that the temperature sensitivity of the fiber Bragg grating was enhanced dramatically by the structure. For example, the temperature sensitivity reached 0.08014 nm/ degrees C when the bimetallic sheets were made of aluminum and iron, which are more than eight times that of a bare fiber Bragg grating. Moreover, it was experimentally demonstrated that the structure has excellent linearity, reversibility, and stability.