Metalens or metalenses, the cutting-edge innovation in optical technology, are not your ordinary, curved lenses. Metalenses are flat lenses that use metasurfaces to focus light.
A metalens differs from a traditional curved lens by its shape and surface. Traditionally, combinations of curved lenses, such as those in cameras, are used to manipulate light to go to a receiver such as a sensor or the eye. Multiple lenses are usually needed in order to correct various image aberrations. However, a stack of bulky lenses takes a lot of space, which is a consideration for compact systems such as cell phone cameras and AR/VR systems.
a) Traditional curved lenses ray trace
b) Metalens ray trace
Metalenses usually consist of millions of subwavelength unit-cells called meta-atoms, which modulate light locally and coherently over the entire metasurface. The shape and/or size of each meta-atom is determined locally based on overall performance of the metalens.
Subwavelength nano-atoms can delay the phase of light, and when properly arranged on the surface, metalenses can create the same desired phase profile as a classic curved lens. Furthermore, patterned layout can be massively produced with mature lithography technology.
Metalenses will be a key enabling technology for the next generation of compact imaging, sensing and display applications. They have the added advantage of being able to perform quite intricate wavefront engineering in a single optic that is highly appealing for a range of applications.
The physical attributes of metalenses – their thin, flat, and lightweight nature – make them incredibly advantageous especially when space and weight are of concern. They have the potential to help with the all-important minimization of optical products by replacing bulkier curved lenses with thin, flat surfaces and improving optical stability and quality of focus over more conventional lenses.[1] They're easy to manufacture, cost-effective, and more amenable to integration with other technologies. Furthermore, due to their superior light-manipulating abilities, for example, polarization, metalenses enhance imagery, potentially openning up new capabilities for optical design.
The development of metasurfaces has helped to open up opportunities for the creation of new types of optical components with new and exciting applications, from sensing in medicine to imaging and consumer electronics, such as smartphones and AR/VR systems.[2] Optical design engineers, R&D engineers, scientists, semiconductor foundries, research institutes, and similar organizations would use metalenses for innovative and compact designs.
Designing a metalens with millions of variables is a uniquely challenging task. You must meet multiple specifications, including achromaticity, large field of view and polarization behaviour with a few elements. As explained in the work of Prof. Federico Capasso’s group [1], metalens design has traditionally been done manually and requires extensive design experience and a deep understanding of fundamental physics.
To design a metalens, a user would need to specify the set of lenses and its parameters in the optical system, as well as the desired target patterns and focus lengths.
In the traditional manual design approach, a deep understanding of physics and significant design experience is needed.
For a semi-automatic multi-domain approach, there is still tremendous manual work to lay out metalenses.
Now a fully automated tool with inverse design capability has been developed so that designers at all levels of expertise can create novel metalens designs quickly and easily. The key design-enabling features of the MetaOptic Designer tool include its ability to simultaneously consider multiple design goals incorporating different launch/ target fields and performance metrics in the context of mixed optical systems composed of multiple metasurface and conventional lenses. The efficient optimization and simulation algorithms generate accurate results, validated by a rigorous finite-difference time-domain (FDTD) method and the powerful and user-friendly features significantly reduce design-to-validation cycles.[1]
Wide angle metalens:
Synopsys, as a leading provider in software, IP, and services, is fueling this wave of optical technology innovation with the MetaOptic Designer, an unprecedented inverse design tool that takes user-specified criteria and generates metalenses/metasufaces for optimal design performance. MetaOptic Designer includes efficient optimization and simulation algorithms to help generate metalens designs quickly. Results are validated by a rigorous finite-difference time-domain (FDTD) method to ensure accurate results. In addition, MetaOptic Designer’s powerful, user-friendly interface significantly reduces design-to-validation cycles. MetaOptic Designer, characterized by its characteristic AI, fast-track design process right from inception to fabrication, delivering top-tier designs and simulating their significance in real-world applications.
Synopsys is supporting this new world of innovation with MetaOptic Designer, an unprecedented inverse design tool that takes user-specified criteria and generates metalenses/metasurfaces for optimal design performance.
1 Electro-Optics article: https://www.electrooptics.com/viewpoint/automation-new-approach-metalens-design
2 "Automation: A new approach to metalens design" - https://www.electrooptics.com/viewpoint/automation-new-approach-metalens-design
