Direct laser writing for micro-optical devices using a negative photoresist

Area of Science:

• Materials Science
• Optical Engineering
• Nanotechnology

Background:

• Direct laser writing (DLW) via two-photon absorption (TPA) is a key microfabrication technique for complex 3D microstructures.
• The ability to create precise micro-optical devices is crucial for advancements in various scientific fields.

Purpose of the Study:

• To fabricate 3D microstructures and micro-optical devices, specifically micro-lens arrays, using DLW with TPA.
• To investigate the influence of irradiation conditions on fabrication parameters like linewidth.
• To evaluate the performance of the fabricated micro-lenses and micro-lens arrays.

Main Methods:

• Utilized a femtosecond laser pulse for TPA-based DLW of the negative photoresist SU-8.
• Investigated the effects of laser power, writing speed, and writing cycles on linewidths.
• Fabricated various 3D microstructures including woodpiles, hemispheres, and micro-lenses.
• Characterized micro-lens shape and working distance using laser microscopy.
• Confirmed focusing performance via TPA fluorescence and demonstrated multi-focusing with a micro-lens array.

Main Results:

• Successfully fabricated complex 3D microstructures and micro-lens arrays on the micrometer scale.
• Optimized irradiation conditions were identified to control linewidths.
• The working distance of fabricated micro-lenses closely matched experimental measurements.
• Demonstrated effective focusing capabilities of the micro-lenses and multi-focusing ability of the micro-lens array.

Conclusions:

• DLW via TPA is a viable method for fabricating high-precision 3D microstructures and micro-optical devices.
• The study validates the design and performance of micro-lens arrays for potential micro-optical applications.
• Further research can explore advanced functionalities and scalability of TPA-based microfabrication.