Design and analysis of photonic crystal fiber-based plasmonic microbiosensor: an external sensing scheme

In this paper, a highly sensitive gold-coated plasmonic microbiosensor, based on photonic crystal fiber (PCF), is proposed and numerically analyzed. To minimize the fabrication challenge and to aid the real-time detection capability of the sensor, the external sensing approach is utilized here. To introduce birefringence property, two rings with some missing air holes are used. Both the wavelength interrogations, as well as the amplitude interrogation method, have been used to determine the sensitivity of the modeled sensor. To demonstrate better performance, different structural parameters, e.g., the thickness of gold layer, pitch, and the diameter of air holes of the PCF, have been varied and investigated. The sensor shows a maximum possible wavelength sensitivity of 10,000 nm/RIU and a maximum possible amplitude sensitivity of 1250 RIU-1 with a sensor wavelength resolution of 1.0 x 10(-5) RIU. The proposed sensor exhibits an admirable figure of merit (FOM) of the highest value of 260.86 RIU-1 with an excellent linearity property of resonance wavelength in terms of analyte refractive indices. The designed sensor reveals promise for sensing and detecting different biological and biochemical liquid analytes of refractive index (RI) ranging from 1.33 to 1.39 with having enhanced performance.