Holy Metal Lens!The new metal lens focuses light in ultra-deep holes

An artistic expression of a perforated metal lens. Credits: Capasso Lab / Harvard SEAS

Metasurfaces are nanoscale structures that interact with light. Today, most metasurfaces use monolith-like nanopillars to focus, shape, and control light. The higher the nanopillar, the longer it takes for light to pass through the nanostructures, giving the metasurface more control over the light of each color. However, very tall pillars tend to fall and stick together. What if instead of building a tall structure, I went in the opposite direction?

In a recent treatise, researchers at Harvard John A. Paulson’s School of Engineering and Applied Sciences (SEAS) have developed a metasurface that focuses on very deep, very narrow holes rather than very high columns. .. Light In a single place.

The study is published at Nano letter..

new Meta surface It uses more than 12 million needle-like holes drilled in a 5 micrometer silicon film, which is about 1/20 the thickness of a hair. The diameter of these long, narrow holes is only a few hundred nanometers, aspect ratio— Height to width ratio — Almost 30: 1.

This is the first time that a hole with such a high aspect ratio has been used for meta-optical.

“This approach can be used to create large achromatic metallics that focus light of different colors to the same focal point, paving the way for the generation of high aspect ratio flat optics with large area wideband achromatic metallics. It will open, “says Federico Capasso. Professor Robert L. Wallace of Applied Physics and Senior Research Fellow Vinton Hayes of Electrical Engineering at SEAS and Senior Author of the Treatise.

Holy Metal Lens!

Scanning electron microscope (SEM) image of the side I hole of the holi metal lens (left) and (right) SEM image of the side II hole of the metal lens. Credits: Capasso Lab / Harvard SEAS

“If you try to make a pillar with this aspect ratio, it will fall over,” says Daniel Lim. graduate student Co-lead author of the treatise at SEAS. “Perforated platforms improve the accessible aspect ratio of optical nanostructures without sacrificing mechanical robustness.”

Like nanopillars of different sizes to focus light, perforated metal lenses have holes of various sizes that are precisely placed over a lens diameter of 2 mm. Changes in hole size bend the light toward the focal point of the lens.

Maryna Meretska, a postdoctoral fellow at SEAS and co-lead author of the treatise, said: “The holes can be filled with non-linear optical materials that lead to the multi-wavelength generation and manipulation of light, or liquid crystals that actively modulate the properties of light.”

Metallence was manufactured using traditional semiconductor industry processes and standard materials, allowing it to be manufactured on a large scale in the future.

Harvard University’s Department of Technology Development is looking for commercialization opportunities to protect the intellectual property associated with this project.

Metasurface controls polarization freely

For more information:
Soon Wei Daniel Lim et al, A High Aspect Ratio Inverse-Designed Holey Metalens, Nano letter (2021). DOI: 10.1021 / acs.nanolett.1c02612

Quote: Holy Metal Lens!The new metallence was obtained from on October 13, 2021 (October 2021). 13th) to focus the light

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Holy Metal Lens!The new metal lens focuses light in ultra-deep holes

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