Enhanced sensitivity in refractive index sensing with open-channel photonic crystal fiber-based plasmonic sensor

Abstract

This study introduces a highly sensitive plasmonic sensor based on a dual-core hexagonal lattice structure photonic crystal fiber (PCF), capable of detecting a broad spectrum of refractive indices (RIs). The sensor’s performance characteristics are assessed using numerical simulations employing the finite element method. To optimize light-metal interaction, double microchannels are strategically positioned on both sides of the sensor. Plasmons are induced through the application of a thin layer of gold to the inner surfaces of these channels. By employing both amplitude and wavelength interrogation techniques, the suggested sensor exhibits an amplitude sensitivity (AS) of 1915.87 RIU⁻¹, a maximum wavelength sensitivity (WS) of 67,000 nm/RIU and a resolution of 1.49 × 10⁻⁶ RIU. It attains a high figure of merit (FOM) of 1914 RIU⁻¹ and demonstrates the ability to detect RIs between 1.33 and 1.44. An analysis of manufacturing tolerances concerning pitch, gold layer thickness, air-hole diameter, channel depth, and channel size is conducted. Due to its expansive sensing range and exceptional sensitivity, the sensor holds promise for applications in detecting biochemical and biological analytes.