High-order diffraction for optical superfocusing.

Area of Science:

• Optics and Photonics
• Nanotechnology
• Materials Science

Background:

• High-order diffraction (HOD) is often problematic in optical microstructures, causing ghosting and efficiency loss.
• Existing methods to suppress HOD, like subwavelength structures, are difficult to scale for large-area manufacturing.
• Independent manipulation of HOD has been a significant challenge, limiting its potential applications.

Purpose of the Study:

• To develop a method for independent manipulation of high-order diffractions (HODs).
• To exploit HODs for achieving subdiffraction-limit focusing in diffractive lenses.
• To demonstrate the practical applications of HOD manipulation in advanced imaging and lithography.

Main Methods:

• Developed an analytical formula to precisely correlate diffraction order with zone width in diffractive lenses.
• Utilized the large spatial frequencies offered by HODs to achieve subwavelength focusing.
• Fabricated diffractive lenses capable of manipulating HOD without requiring subwavelength features.

Main Results:

• Achieved lateral focal sizes down to 0.44λ, surpassing conventional diffractive lens limitations.
• Demonstrated high-order lens-based confocal imaging with a record center-to-center dry resolution of 190 nm.
• Successfully performed laser-ablation lithography with a direct-writing resolution of 400 nm (0.385λ).

Conclusions:

• Independent manipulation of HOD provides a novel pathway for subdiffraction-limit focusing.
• The developed method facilitates large-scale manufacturing of high-performance diffractive lenses.
• This technique significantly advances the resolution capabilities of visible-light confocal microscopy and laser-based nanofabrication.