Metasurface Phased Array: Grating Lobes vs Generalized Snell's Law

What Metasurfaces Are

Metasurfaces are artificially engineered surfaces that can manipulate electromagnetic waves at will, offering unprecedented control over light and other forms of radiation. These surfaces consist of subwavelength structures arranged in a pattern to achieve specific optical properties.

The key feature of metasurfaces is their ability to steer beams of light or other waves by adjusting the phase and amplitude of individual elements, which can be achieved through precise design and fabrication techniques.

Grating Lobes and Generalized Snell's Law

Grating lobes occur when a metasurface is used to steer electromagnetic waves. These lobes are additional peaks in the far-field pattern that arise due to interference between different paths taken by the wavelets from each element of the array.

Generalized Snell’s law describes how these wavelets interact and interfere, leading to anomalous steering angles that differ significantly from those predicted by classical refraction laws.

Interference Patterns in Metasurfaces

In a metasurface phased array, the near-field panel displays the Huygens-wavelet interference pattern. This pattern is crucial for understanding how individual elements contribute to the overall wavefront and how their phases are controlled.

The far-field strip plot shows the exact array-factor diffraction pattern, marking both the generalized Snell’s law lobe and any grating lobes that may appear due to constructive or destructive interference.

Applications of Metasurfaces

Metasurfaces find applications in various fields such as optics, antenna design, and even in the development of new types of displays.

By precisely controlling the phase step and element pitch, researchers can create devices that can dynamically switch between different functionalities, making them highly versatile.

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