A novel temperature insensitive refractive index sensor based on dual photonic crystal fiber

A novel dual photonic crystal fiber (DPCF) temperature insensitive refractive index sensor is proposed in this article. By sequentially splicing lead-in SMF (single mode fiber), PCF_1, PCF_2, and lead-out SMF constitute the Mach-Zehnder interferometer (MZI). The refractive index sensitivity (RIS) of the proposed sensor is improved by making an abrupt-taper on the fusion point of two PCFs. The proposed sensor is compared with a sensor without an abrupt-taper, the RIS value of the proposed sensor is increased by ∼1.9 times. The collapsed area of two photonic crystal fiber air holes is used as a beam splitter and combiner of Mach-Zehnder interferometer. Experimental analysis indicates that the RIS is 152.97 nm/RIU (1.330–1.383 RIU). Besides, the proposed sensor is independent of temperature and its sensitivity towards temperature is only -0.0045 nm/°C (30−80 °C). This sensor has the characteristics of relatively high sensitivity, ease of fabrication, and compact size.