Shifting surface plasmon resonance wavelength to the far-ultraviolet region with aluminum-based sensors

A novel aluminum (Al)-based surface plasmon resonance (SPR) sensor operating in the far-ultraviolet (FUV, <200 nm) region has been developed. By utilizing a thinner Al film compared to previously reported deep-ultraviolet (DUV, <300 nm) SPR sensors, the SPR wavelength was effectively maintained within the FUV region across various liquids. In the presence of resonant molecules, the SPR wavelength shift was notably enhanced. Additionally, optimizing the incident light angle further improves sensitivity owing to narrower and deeper SPR dips. The design adjustments including Al film thickness and incident light angle, were guided by numerical simulations based on the Fresnel equations. These advancements enable the selective detection of molecules with specific FUV absorption characteristics.