Plasmonic Nanolenses Produced by Cylindrical Vector Beam Printing for Sensing Applications

Area of Science:

• Plasmonics
• Nanophotonics
• Optical Engineering

Background:

• Complex-shaped light fields interacting with plasmonic nanostructures enable unique optical phenomena.
• Conventional fabrication methods for these nanostructures are expensive and time-consuming.
• There is a demand for cost-effective fabrication techniques for plasmonic nanostructures designed for complex light fields.

Purpose of the Study:

• To demonstrate a simple, maskless, laser-based fabrication approach for plasmonic nanorings.
• To achieve efficient nanofocusing of surface waves using these nanostructures.
• To enable applications in nanophotonics and biosensing.

Main Methods:

• Fabrication of metal-insulator-metal (MIM) nanorings using laser ablation with donut-shaped pulses.
• Post-fabrication polishing using argon ion-beam.
• Excitation of nanorings with radially polarized beams.
• Finite Difference Time Domain (FDTD) calculations for optical simulations.
• Experimental verification using photoluminescent signal enhancement.

Main Results:

• Successful fabrication of back-reflector-coupled plasmonic nanorings arrays.
• Efficient nanofocusing of plasmonic waves in the gap area of MIM nanorings.
• Achieved substantial enhancement of electromagnetic near-fields (0.37λ² focal spot size).
• Observed a 100-fold enhancement in photoluminescent signal from organic dye molecules.

Conclusions:

• The demonstrated laser-based approach offers a simple, scalable, and cost-efficient method for fabricating plasmonic nanostructures.
• The fabricated MIM nanorings exhibit remarkable optical and plasmonic properties, enabling efficient light nanofocusing.
• These structures hold promise for developing advanced nanophotonic and biosensing platforms utilizing cylindrical vector beams.