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Do you know what metalenses are? Metalenses can control light by its surface properties and can be flat and thin. Spherical aberrations are not an issue and these special lenses can replace bulky curved lenses. This has the potential to reduce the amount of lenses in a system and create compact lens systems for imaging, sensing, and display applications.
A few years ago, Samsung combined metalenses and refractive lenses to develop a smartphone camera sensor surpassing 100 megapixels.[1] LG developed an ultrathin camera metalens for self-driving electric vehicles. Metalenses pave the way for drastic miniaturization of imaging systems like electric vehicles cameras, and they can also be used in phones and various other micro-camera applications.[2] In addition, researchers in the U.S. used a common semiconductor manufacturing process to produce a large aperture, flat metalens. It was used as the objective lens in a simple telescope, and it achieved superior resolving power and produced clear images of the surface of the Moon.[3]
Though metalenses are a promising advance in scaling down the size of optical systems, there are challenges, both in designing them and manufacturing them to scale.
One challenge with metalenses is designing a metalens with millions of variable subwavelength unit-cells, called meta-atoms, to modulate light locally and coherently requires design experience and a deep understanding of fundamental physics. Metalens designs involve defined lens phase profiles, a meta-atom library, and layout of the meta-atoms on the metalens surface. Then, the optical designer must choose an approach to simulate the built metalens to evaluate its performance.
If manually designing a metalens, the approach relies on a pre-defined phase profile, which is valid for a fixed incident condition only because the transfer function of the meta-atoms varies at different wavelength, incident angle, and polarization. Therefore, a phase profile optimized at a particular incident condition is not valid at others. As a result, it is very difficult to design a metalens with multiple functions, such as an achromatic lens for a wide spectral range or a large field of view (FOV) lens for wide incident angles.[4]
Could there be a user-friendly design tool to automate metalens design for engineers to design metalens systems quickly and easily? Though significant efforts have been made worldwide to develop automation flows with inverse design capabilities, 草榴社区 has developed the first fully automated commercial tool, MetaOptic Designer, that provides inverse design capabilities for metaoptics. The optimization algorithm employs the well-known adjoint method, which can easily handle millions of design variables.
To design a metalens in MetaOptic Designer, the user specifies the set of lenses in the optical system and the BSDF database for each, as well as the desired target patterns and focus lengths. Then, the tool determines the design parameters across each metasurface and exports GDS and optimization results, shown in figure 1.
Figure 1: MetaOptic Designer Overview
Now, optical designers can have a dramatically simplified and speedier design workflow when designing a metalens, with minimum inputs required.
Will metalenses revolutionize the industry? Lead researcher at Pennsylvania State University believes that metasurfaces can be a game changer in optics, because their unprecedented capability for light manipulation makes them powerful candidates for next-generation optical systems.[5] On a nanoscale, metalens can also be used to focus vacuum ultraviolet light on a small spot less than 2 microns in diameter from intricate nanostructures with a zinc oxide thin film.[6]
There’s no question that there will be a demand for compact lens systems and that many more designs will incorporate metalenses. Now, we’re paving a way for designers at all levels of expertise can create novel metalens designs quickly and easily, with accurate optimization results.
To learn more about MetaOptic Designer, see the resources below, or contact us at optics@synopsys.com to request a free demo.
References
- Villas-Boas, A. (August 12, 2019). Samsung just unveiled the first smartphone camera that goes beyond 100 megapixels. Business Insider.
- Zlatev, D. (July 6, 2022). LG developing ultrathin camera metalens for compact and frugal electric vehicle self-driving kits. NotebookCheck.
- Telescope with large-aperture metalens images the Moon.
- Xu, Chenglin (January 2023). 草榴社区. “MetaOptic Designer: Automated Design of Metalenses.”
- Telescope with large-aperture metalens images the Moon. https://physicsworld.com/a/telescope-with-large-aperture-metalens-images-the-moon
- New meta-lens revolutionises vacuum UV optics (July 27, 2022).