Photonic crystal fiber refractive index temperature sensor based on double spherical cascade

Abstract

A dual spherical photonic crystal fiber (PCF) Mach-Zender refractive index temperature sensor is proposed. The sensing structure is a PCF fused to a spherical structure made of two single-mode fibers, of which the two spherical structures serve as beam splitter and coupler, respectively, for refractive index sensing experiments. In addition, temperature sensing experiments were conducted by filling the middle PCF with ethanol using the same structure. Experimental results show a maximum sensitivity of 190.26 nm/RIU for the wavelength drift of the resonance valley of the interference spectrum in the refractive index range of 1.348–1.358. The maximum sensitivity of the wavelength drift of the resonant valley of the interference spectrum is − 0.306 nm/°C for temperatures in the range of 40–50 °C. The sensor studied in this paper is characterized by high sensitivity, simple manufacturing, and low cost.