Plasmonic direct-writing lithography via high numerical aperture objectives.

Area of Science:

• Optics and Photonics
• Nanotechnology
• Materials Science

Background:

• Sub-wavelength light-matter interactions require advanced, flexible, and low-cost nano-patterning tools.
• Plasmonic lithography offers precise light confinement but typically relies on pre-defined metallic nanostructures, increasing fabrication complexity and cost.

Purpose of the Study:

• To develop and demonstrate an antenna-free plasmonic lithography technique.
• To achieve high-resolution nano-patterning with simplified fabrication processes.
• To explore the use of high numerical aperture objectives in plasmonic lithography.

Main Methods:

• Numerical simulations and experimental validation of a novel plasmonic lithography technique.
• Utilizing high numerical aperture (NA) objectives as scanning heads without pre-defined metallic nanostructures.
• Employing back-focal-plane imaging for precise surface-plasmon excitation visualization and focus adjustment.

Main Results:

• Demonstrated minimum feature sizes of 0.36λ/NA (numerically) and 0.46λ/NA (experimentally).
• Achieved sub-wavelength patterning using linearly polarized continuous-wave illumination at 457 nm.
• Confirmed the absence of nonlinear effects in the patterning process.

Conclusions:

• The developed antenna-free plasmonic lithography offers a convenient and economical approach for nano-patterning.
• This technique is suitable for laser processing at the sub-wavelength scale.
• High NA objectives can effectively replace complex metallic nanostructures in plasmonic lithography.