A new approach to manufacturing multicolour metalenses could inspire the next generation of tiny, affordable, and high-performance optics for portable devices such as smartphones, drones, and imaging systems.

The design uses layers of metamaterials to simultaneously focus a range of wavelengths from an unpolarised source and over a large diameter — overcoming a major limitation of conventional metalenses, said first author Mr Joshua Jordaan, from the Research School of Physics at the Australian National University (ANU) and the ARC Centre of Excellence for Transformative Meta-Optical Systems (TMOS).

A Scalable Meta-Optics Breakthrough

This multilayer design is simple to manufacture because it has a low aspect ratio, and each layer can be fabricated individually and packaged together. It is also polarisation-insensitive and potentially scalable through semiconductor nanofabrication platforms — an important step toward mass-production of advanced meta-optical components.

The project was led by researchers from the Friedrich Schiller University Jena in Germany as part of the International Research Training Group Meta-ACTIVE. Their paper reporting the design has been published in Optics Express. Read the full paper here.

Why Meta-Optics Matters

Metalenses are ultra-thin — just fractions of the width of a human hair — making them much lighter than traditional glass lenses. They can also achieve optical properties, such as very short focal lengths, that are impossible with conventional optics.

Initially, the team attempted to focus multiple wavelengths using a single metasurface layer but found it was physically limited. To work across the wavelength range they needed, the lens would have required a very small diameter (defeating the purpose) or such a low numerical aperture that it would barely focus light at all.

The solution was a multi-layer meta-optical approach.

Advanced Inverse Design Optimisation

The researchers used an inverse design algorithm with shape optimisation to generate new metasurface geometries. By guiding the software to look for structures that created Huygens resonances (electric and magnetic dipole resonances), the team produced metalens designs that were:

• Polarisation-independent

• More tolerant of fabrication errors

• Better suited to industrial-scale production

The optimisation routine created a diverse library of metamaterial elements in shapes such as rounded squares, four-leaf clovers, and propellers. These nanostructures — around 300 nm tall and 1000 nm wide — spanned the full range of phase shifts needed to achieve arbitrary focusing patterns.

Applications for Drones, Smartphones, and Satellites

While the multilayer approach is currently limited to about five wavelengths, it still enables powerful applications in portable imaging systems.

With their ability to collect more light, these meta-optical lenses could transform the future of smartphone cameras, drone vision systems, and satellite imaging, driving innovation in consumer electronics and aerospace.

Learn More

This research is another example of how TMOS is pushing the boundaries of meta-optics and nanophotonics. Read the original article on the ANU Physics website.