Aluminium-Based Plasmonic Sensors in Ultraviolet.

Area of Science:

• Plasmonics
• Nanophotonics
• Optical Sensing

Background:

• Surface plasmon polaritons (SPPs) are electromagnetic waves propagating at the interface of a metal and a dielectric.
• SPPs are highly sensitive to changes in the dielectric's refractive index, making them suitable for sensing applications.
• Ultraviolet (UV) plasmonics offers potential for miniaturized and high-resolution sensing devices.

Purpose of the Study:

• To theoretically investigate the generation and properties of SPPs on an aluminum (Al) film coated with an aluminum oxide (Al2O3) layer.
• To evaluate the potential of this system as a refractive index sensor operating in the UV wavelength range.
• To analyze the influence of geometric parameters and surface roughness on sensor performance.

Main Methods:

• Theoretical investigation using calculations of reflection spectra.
• Modeling of SPP resonance excitation by ultraviolet light.
• Analysis of the impact of metal and oxide layer thicknesses on resonance characteristics.
• Simulation of sensor performance metrics like quality factor and figure of merit.

Main Results:

• SPP resonance was observed in the UV range (150-300 nm), tunable by layer thicknesses.
• An optimized geometry achieved a quality factor of up to 10 and a figure of merit of 9.
• The sensor demonstrated the capability to detect a 1% change in refractive index.
• Performance was found comparable to more complex UV plasmonic nanostructures.
• Sensitivity to incidence angle, wavelength, and amplitude changes was confirmed, including the effect of oxide surface roughness.

Conclusions:

• The Al/Al2O3 system is a promising platform for UV refractive index sensing.
• Optimized designs offer high sensitivity and performance comparable to advanced nanostructures.
• The sensor's tunability and robustness to surface roughness highlight its practical potential.