New Metamaterial Lenses Promise Compact, Multicolor Optics
A cutting-edge approach to manufacturing multicolor lenses could transform the optics inside portable devices, including smartphones and drones. Researchers have developed a multi-layer metalens design that can simultaneously focus a broad range of wavelengths from unpolarised light, while maintaining a small form factor and large diameter. The breakthrough could lead to lighter, cheaper, and more capable cameras on everyday devices.
The team, led by Joshua Jordaan of the Research School of Physics at the Australian National University and the ARC Centre of Excellence for Transformative Meta-Optical Systems (TMOS), emphasizes practical attributes in their design. “Our design has a lot of nice features that make it applicable to practical devices,” Jordaan noted. The approach is described in Optics Express, outlining how layered metamaterials overcome limitations inherent in conventional metalenses.
Why Multilayer Metalenses Help Portable Imaging
Traditional single-layer metasurfaces face physical constraints that cap how much light they can gather and how broadly they can operate across wavelengths. In a single layer, the maximum group delay and the product of numerical aperture, diameter, and bandwidth create tight restrictions. To address this, the researchers adopted a multilayer strategy that unlocks greater flexibility and performance.
“A single layer would either have to be tiny in diameter or exhibit a very low numerical aperture that fails to focus light effectively,” explained Jordaan. “By moving to multiple layers, we can design more complex phase control and resonances to handle a wider spectrum of light.”
The core concept relies on Huygens resonances—inducing specific electric and magnetic dipole resonances—to shape light. Through an inverse design algorithm with shape optimization, the team generated a diverse library of metamaterial elements. The resulting elements include shapes such as rounded squares, four-leaf clovers, and propellers, all about 300 nanometers tall and 1 micrometer wide, capable of spanning the full phase range from zero to two pi. This enables a programmable phase gradient map suitable for arbitrary focusing patterns.
Polarisation-Insensitive and Scalable
A key advantage of the multilayer approach is its polarisation insensitivity, which simplifies real-world use. The layers can be manufactured separately with a low aspect ratio and then packaged together, a process compatible with mature semiconductor fabrication platforms. This aligns the technology with scalable production pipelines, an important step toward integrating advanced optics into consumer devices.
The researchers acknowledge some limits: the multilayer system can effectively handle up to about five distinct wavelengths before diffraction and resonance concerns become prohibitive. Even within this constraint, the potential impact is substantial for portable imaging systems that demand compact, light, and efficient optics.
Practical Implications for Drones and Mobile Devices
In practice, these multilayer metalenses could significantly improve camera performance in small form factors. For drones, lightweight optics with high light-gathering capability translate into longer flight times and sharper aerial imagery. For smartphones and other portable devices, the prospect of cheap, tiny, and robust multicolor lenses could enable new imaging features and better low-light performance without increasing bulk or cost.
“The metalenses we have designed would be ideal for drones or earth-observation satellites, as we’ve aimed to make them as small and light as possible,” said Jordaan. The team’s work underscores a broader movement toward metamaterial-based optics that can outperform traditional lenses while fitting within existing manufacturing ecosystems.
Looking Ahead
While the current design focuses on a maximum of five wavelengths, ongoing refinements and broader wavelength strategies could push this boundary further. The combination of polarization insensitivity, manufacturability, and scalable production positions multilayer metalenses as a promising platform for next-generation portable imaging. As researchers continue to optimize materials and fabrication processes, the dream of ultra-compact, multicolor, high-performance optics for phones and drones moves closer to mainstream reality.
