Sensing characteristics of all-solid photonic bandgap fiber modal interferometers

We demonstrate an all-solid photonic bandgap fiber modal interferometer by concatenating two tapers separated with a middle section of the fiber. Unlike the conventional devices, our structure has a lower effective index in the core and a higher effective index in the cladding, which produce novel sensing characteristics. The measured sensing sensitivities are ~63pm/°C for temperarure and ~1.74nm/N for the axial stress, respectively.