Fabrication of inclined non-symmetrical periodic micro-structures using Direct Laser Interference Patterning

Area of Science:

• Materials Science
• Nanotechnology
• Optics

Background:

• Inclined microstructures offer anisotropic properties, mimicking natural surfaces and attracting research interest.
• Direct fabrication of non-symmetrical, inclined microstructures remains a significant microfabrication challenge.

Purpose of the Study:

• To present a microfabrication technique for producing microstructures with controllable inclination angles.
• To explore the correlation between structuring parameters and microstructure inclination.
• To demonstrate the potential for creating direction-dependent properties in polymeric materials.

Main Methods:

• Utilized two-beam Direct Laser Interference Patterning (DLIP) with a 4 ns UV (266 nm) laser source.
• Irradiated polyimide foils to create line-like microstructures with periods ranging from 4.6 µm to 16.5 µm.
• Controlled inclination angles from 0° to 75° by tilting the sample relative to the optical axis.

Main Results:

• Achieved well-defined and controllable inclination angles for microstructures.
• Established a correlation between laser fluence, pulse number, interference period, and microstructure inclination.
• Observed remarkable non-symmetrical morphology and structural undercuts at specific laser fluences and pulse numbers.
• Demonstrated preliminary light diffraction results similar to blazed diffraction gratings.

Conclusions:

• The DLIP technique enables precise control over microstructure inclination and morphology on polyimide.
• The ability to create undercuts opens avenues for novel direction-dependent properties in polymers.
• The fabricated structures show potential for applications in optics, such as blazed diffraction gratings.