High Numerical Aperture Metalens for the Deep Ultraviolet

Area of Science:

• Optics and Photonics
• Materials Science
• Nanotechnology

Background:

• Deep-ultraviolet (DUV) radiation is crucial for advanced nanofabrication and biomedical imaging.
• The lack of compact, high-performance DUV optical components hinders technological progress.
• Aluminum nitride (AlN) is a promising material for DUV optical applications.

Purpose of the Study:

• To demonstrate a high-numerical-aperture (HNA) metalens operating in the DUV spectral range.
• To establish a novel characterization method for HNA DUV metalenses.
• To integrate HNA AlN metalenses into advanced imaging systems.

Main Methods:

• Fabrication of an AlN metalens with a high numerical aperture (NA) of 0.9-0.7 at 266 nm.
• Optical measurements to confirm diffraction-limited focusing.
• Development of direct laser writing microscopy (DLWM) for characterization and nanofabrication.
• Integration of the metalens into a confocal photoluminescence imaging system.

Main Results:

• Achieved record-high numerical aperture (NA=0.9-0.7) for a DUV metalens at 266 nm.
• Demonstrated diffraction-limited focusing performance.
• Utilized DLWM for 100 nm critical dimension nanofabrication and universal HNA DUV metalens characterization.
• Enabled sub-micrometer spectroscopic imaging and resolved 300 nm features using the metalens in a confocal photoluminescence system.

Conclusions:

• AlN metalenses offer a transformative platform for high-resolution DUV applications.
• The developed DLWM provides a universal characterization technique for HNA DUV metalenses.
• HNA AlN metalenses enable compact and high-performance DUV spectroscopic imaging systems.