In this paper, simultaneous measurement of temperature and external refractive index (RI) is achieved in the presented scheme, which is based on a Mach–Zehnder interferometer using a nonadiabatic single-mode fiber taper without an air cavity. This scheme is quite simple, and the smallest diameter of the tapered fiber is about 83.1 μm and the length of tapered fiber is about 1 cm. The transmission spectrum of the nonadiabatic tapered fiber exhibits a number of resonance wavelength dips that correspond to different orders of cladding modes. The interferometer can be used for simultaneous RI and temperature sensing by monitoring the variation of two selected wavelength dips. The sensitivities achieved are −44.69 nm/RIU and 0.0386 nm/°C and −72.21 nm/RIU and 0.0321 nm/°C for the RI and temperature, respectively. The proposed tapered single-mode optical fiber interferometer would find potential applications in multiple-parameter sensing owing to its high sensitivity, compactness, ease of fabrication, and low cost.
© 2018 Optical Society of AmericaPDF Article