Sensitivity of a tapered fiber refractive index sensor at diameters comparable to wavelength

While there is an established literature on the effect of geometric parameters and material properties on the sensitivity of tapered fiber refractive index sensors, the impact of these parameters has been largely overlooked at sensor at diameters comparable to wavelength. Here, we investigate the effect of geometric parameters and materials properties at dimensions comparable to wavelength using full-wave solutions of Maxwell’s equations. Our results indicate that to achieve the maximum sensitivity for the tapered fiber sensors, the diameter should be closer to operational wavelength. For diameters less than the operational wavelength, sensitivity reduces instead of further increasing, a phenomenon opposite to what was predicted by ray-tracing based tapered fiber models. Another important finding of this study is the effect of optical loss constant on the sensitivity, a parameter often overlooked in the literature. As the optical loss constant was varied from 0 to 0.04 for each iteration of RI variation range, a linear decrease in sensitivity from 0.12 trans. (A.U)/RIU to 0.05 trans. (A.U)/RIU.