Enhancing the Sensitivity of a Surface Plasmon Resonance Sensor with Glancing Angle Deposited Nanostructures

In this paper, we demonstrate that the glancing angle deposition (GLAD) technique is a competitive and efficient method to fabricating a nanostructured surface that enhances the sensitivity of surface plasmon resonance (SPR) sensors, because of its simplicity and unique characteristics of material selection. The theoretical investigations were conducted by employing a rigorous coupled-wave analysis for design metrics, i.e., shift in resonance angle, SPR curve angular width, and minimum reflectance at resonance. An optimized geometry was achieved with enhanced characteristics of the SPR sensor. The SPR features of hybrid GLAD nanostructures deposited onto metallic thin films were investigated. An optical setup that used the Kretschmann-Reather configuration was utilized to monitor changes in the refractive index of water solution using the optical power interrogation method. The experimental results demonstrate that the SPR sensor fabricated with hybrid GLAD nanostructures of 30 nm height and ~ 12 nm inter-structural gap size achieved the sensitivity ~ 4× higher that of a than conventional SPR sensor.