A collection of small antennas can amplify and control polarization in any direction

Antennas receive and transmit electromagnetic waves, and distribute information to radio, television, mobile phones, etc. Researchers at McKelby’s Faculty of Engineering at Washington University in St. Louis imagine a future in which antennas will rebuild even more applications.

Their new metasurface, ultra-thin material made with small nano-antennas that can amplify and control light in a very accurate way, replaces traditional refractive surfaces from glasses to smartphone lenses, augmented reality/virtual reality and LIDAR Dynamic applications such as photodetection (photodetection) and range.

Metasurfaces can manipulate light very accurately and efficiently, allowing for powerful optical devices, but often suffer from major limitations. Metasurfaces are very sensitive to the polarization of light. This means that it can interact with light that oriented and travels in a specific direction. This is useful in polarized sunglasses and other communication and imaging technologies that block glares, but the need for specific polarization dramatically reduces the flexibility and applicability of metasurfaces.

To overcome this obstacle, a team led by Mark Lawrence, an assistant professor at Preston M. Green Electrical Systems Engineering, demonstrated a highly polarization-independent, highly resonant metasurface that maintains high accuracy and efficiency. The results are published on Nano Letters.

“Combining these small antennas to form light waves allows us to move away from relying on glass or other refractive materials in the shape,” Lawrence said. “We can scale down, design and shape devices the way we like, yet still operate light accurately and efficiently.”

Lawrence’s polarization-independent metasurfaces are known as high quality factors. In other words, it traps light in a narrow band of resonance frequencies for a long time, creating a strong response to external stimuli. This sensitivity allows for enhancements to open new applications for optical stimulation.

“We’re not only making the metasurface smaller, but we’re embedding new features,” Lawrence added. “For example, by resonating and amplifying light within the device, creating glasses that translate and understand incoming information from the wearer, or changing focus or manipulate the light as the user desires. You can create a programmable lens to do so.”

Previous iterations of highly resonant metasurface teams only achieve these advanced properties when illuminated with a specific polarization. However, with a new approach to Metasurface manufacturing, polarizers are no longer needed.

Lawrence and author Bo Chao, a graduate student in Lawrence and Lawrence’s group, designed a metasurface with two intersecting polarization modes that function independently and coordinated. Careful alignment and tuning of the two modes allows the metasurface to manipulate multiple polarizations simultaneously without losing efficiency or other desirable quality.

The meaning of this work goes beyond improving the versatility of metasurfaces. By enabling highly resonant polarization-independent wavefront geometry, the new metasurface unlocks new methods for nonlinear generation and light mixing, signal processing, quantum device design, and other This can lead to breakthroughs in imaging and sensing applications.