Diffusion-assisted high-resolution direct femtosecond laser writing.

Area of Science:

• Materials Science
• Nanotechnology
• Photochemistry

Background:

• Direct laser writing (DLW) via multiphoton polymerization enables 3D microfabrication.
• Achieving sub-500 nm resolution in DLW remains a significant challenge.
• Existing high-resolution techniques often require complex setups like stimulated-emission-depletion (STED) microscopy.

Purpose of the Study:

• To introduce a new, simpler method for enhancing the resolution of DLW.
• To demonstrate the fabrication of high-resolution 3D structures using the proposed technique.
• To investigate the underlying mechanism responsible for the resolution enhancement.

Main Methods:

• Utilizing quencher diffusion in conjunction with slow laser scanning during multiphoton polymerization.
• Employing an organic-inorganic hybrid material and a photopolymerizable amine-based monomer as the quencher.
• Fabricating woodpile structures and characterizing their optical properties.

Main Results:

• Achieved woodpile structures with a 400 nm intralayer period, demonstrating sub-500 nm resolution.
• Optical characterization revealed well-ordered diffraction patterns and stopgaps extending to near-infrared wavelengths.
• Modeling confirmed that quencher diffusion and subsequent radical inhibition are responsible for the improved resolution.

Conclusions:

• The quencher diffusion method offers a straightforward approach to significantly enhance DLW resolution.
• This technique provides a viable alternative to complex STED-based methods for high-resolution 3D fabrication.
• The developed method opens possibilities for fabricating intricate nanostructures with precise optical properties.