Recent Applications of Tapered Multicore Fiber in Optical Sensing: A Review

This review presents the current applications of tapered multicore fiber (TMCF)-based optical sensors in single- and multiparameter sensing. Refractive index (RI)- and temperature-based TMCF sensors are the most widely used candidates. A trench-assisted TMCF sensor demonstrated a sensitivity of 35089.28 nm/RIU within a surrounding RI (SRI) range of 1.4430-1.4442, the highest reported sensitivity to date among RI sensors. Moreover, TMCF RI-sensor designs for temperature-insensitive operation and in situ temperature compensation have been reported. Additionally, the RI-insensitive designs of TMCF temperature sensors were investigated, and a maximum sensitivity of 103.2 pm/degrees C was obtained. Furthermore, TMCF sensors for measuring strain, curvature, magnetic field, and torsion as well as a localized surface plasmon resonance (LSPR) integrated TMCF biosensor have been reported and discussed. TMCF sensors have shown promise in multiparameter sensing; however, few reports have been provided in the literature. The potential for multiparameter sensors is significant due to the higher sensitivity of interference-based sensors to alterations in the effective RI of the optical path. Maximum RI and temperature sensitivities of 5815.50 nm/RIU and 0.1084 nm/degrees C have been reported for the TMCF configuration as a multiparameter sensor, respectively. This review serves as a significant resource for researchers who are interested in the area of optical sensing and the design of sensors based on TMCF.