Single-mode all-fiber structured modal interference for temperature and refractive index sensing

A new type of optical fiber sensor based on an asymmetric structured microfiber modal interferometer is proposed and demonstrated. The sensor head is simply made of single-mode fiber using the electrical arc discharge technique. Owing to the reflection spectrum dips formed by the interference between the cladding modes and the core mode, measurements of temperature and the refractive index (RI) can be obtained by monitoring the wavelength shifts of the interference spectrum. Experiments show that the sensor exhibits a good response to temperature and the ambient RI variation, with maximum sensitivities of 0.079 nm degrees C-1 and -49.957 nm/RIU, respectively. The merits of its cost-effective and simple fabrication makes this sensor a promising device for sensing applications.