Laser beam lithographed micro-Fresnel lenses

Area of Science:

• Optics and Photonics
• Microfabrication Technologies
• Nanotechnology

Background:

• Micro-Fresnel lenses (MFLs) are crucial optical components for miniaturized systems.
• Traditional fabrication methods like electron-beam lithography face limitations in resolution and scalability.
• Developing advanced lithography techniques is essential for high-performance MFLs.

Purpose of the Study:

• To propose and demonstrate laser beam lithography for fabricating micro-Fresnel lenses with blazed grooves.
• To evaluate the resolution, diffraction efficiency, and spot size characteristics of laser beam lithographed MFLs.
• To showcase the application of these MFLs in integrated optics and laser Doppler velocimetry.

Main Methods:

• Laser beam lithography system configuration and process parameters.
• Fabrication of micro-Fresnel lenses with blazed gratings in resist.
• Characterization of MFLs, including resolution, diffraction efficiency, and optical performance.
• Integration of MFLs with optical waveguides and application in a laser Doppler velocimeter.

Main Results:

• Achieved resolution superior to electron-beam lithography for 1-microm deep relief gratings.
• Demonstrated large-diameter (9.6 mm) and compact (N.A. 0.21) MFLs.
• Obtained nearly diffraction-limited spot sizes with diffraction efficiencies exceeding 50% for fabricated MFLs.
• Presented a specific MFL array for integrated optic laser Doppler velocimeter applications.

Conclusions:

• Laser beam lithography is a viable and high-performance technique for fabricating micro-Fresnel lenses.
• The demonstrated MFLs exhibit excellent optical characteristics suitable for various applications.
• This technology offers a promising route for advanced integrated optical systems.