Introducing Heidelberg's Fabrication of Refractive Micro-Lenses for Advanced Photonics Applications

The fabrication of refractive micro-lenses is crucial for advanced photonics applications like telecommunications, optical tweezers, and electromagnetic wave manipulation. In our latest application note, we demonstrate together with GermanLitho how the integration of Direct Laser Writing (DLW) and Nanoimprint Lithography (NIL) enables the efficient creation of micro-lenses for generating Orbital Angular Momentum (OAM) in light waves.

Key Findings

Refractive micro-lenses offer distinct advantages over traditional Diffractive Optical Elements (DOE), which often suffer from inefficiencies such as low diffraction efficiency and chromatic aberrations. By utilizing DLW, smooth, grayscale 2.5D structures can be fabricated with high precision, ensuring better optical performance for focusing light waves carrying OAM modes.

In this application, we focus on the fabrication of a unique optical element that integrates a Spiral Phase Plate (SPP) with a spherical micro-lens. This combination allows the transfer of OAM to incoming light while simultaneously focusing it into a small ring, streamlining the process and eliminating the need for multiple components in the optical path. Heidelberg DWL 66+ system was critical in the process, allowing precise control over the grayscale values that define the micro-lens shape.

Combining DLW and NIL: Scalable Precision from Prototype to Volume Production 

The strength of this approach lies in the synergy between Direct Laser Writing and Nanoimprint Lithography. DLW enables the creation of high-resolution, custom grayscale structures directly onto a photoresist layer. Once the master structure is produced through DLW, NIL provides a cost-effective way to replicate these complex patterns across a wide range of substrates, from small-scale prototypes to larger volumes. This two-step process allows for high throughput without sacrificing precision, making it ideal for industries requiring both flexibility and scalability.

Benefits for Photonics Applications

This method is not limited to the current application but can be extended to a wide range of refractive micro-optics, allowing for significant advancements in fields such as fiber-optic communications and biomedical optics. The use of NIL for replicating the structures created by DLW ensures that these advanced optical elements can be produced efficiently and accurately for both research and industrial use.

Advantages of the DWL 66+

The DWL 66+ Laser Lithography System stands out for its:

• 1024 grayscale levels for accurate surface profile generation.

• High-resolution exposure for both grayscale and binary structures.

• Ability to produce complex micro-optical elements in just a few iterations.

This precision makes it ideal for research and production environments requiring reliable, reproducible optical elements. Additionally, the combination with NIL technology facilitates the rapid replication of these elements, enabling small- to large-scale production.

Conclusion

The combination of Direct Laser Writing and Nanoimprint Lithography represents a powerful method for fabricating refractive micro-lenses with precise optical characteristics. This approach not only enhances performance in cutting-edge photonics applications but also offers a scalable solution for rapid replication and production, bringing innovation and efficiency to the forefront of micro-optics fabrication.