Highly sensitive plasmonic sensor based on scaled down air holes assisted photonic crystal fiber for biosensing applications

A newly designed photonic crystal fiber (PCF) based plasmonic sensor is proposed for label free biological analyte detection applications. A advanced designing approach is proposed by introducing scaled down air holes to form a light leakage channel when the core is at fiber center. Gold film and an overlayer of high refractive index TiO2 films are coated in nanoscale regime outside the fiber periphery for efficient sensing response. By analyzing modal characteristics numerically by using finite element method (FEM), the wavelength sensitivity is found to be varied nonlinearly up to 30,000 nm/RIU within the analyte detection range from 1.320 to 1.375 RIU (refractive index unit) and minimum reported sensitivity is 4000 nm/RIU. Moreover, the minimum measurable deviation of the sensor lies of the order of 10−6 with a high figure of merit (FOM) up to 550 RIU−1 representing an overall good sensing performance. The proposed fiber has good specificity, environmental stability, small size and feasible optical sensing properties which enables its suitability to be an optical component of biosensor.