Metasurfaces & Flat Optics

Physics / mechanism

Metasurfaces are 2D arrays of sub-wavelength resonators (meta-atoms — typically titanium dioxide, silicon, or GaN pillars, 50–400 nm feature size) patterned on a substrate to locally manipulate phase, amplitude, and polarisation of incident light. By engineering each unit cell’s geometry, a single planar element replaces stacked refractive/diffractive components. Key parameters: operating wavelength, numerical aperture (demonstrated up to 0.9 in visible), diffraction efficiency (best-in-class TiO₂ ~90% at 532 nm), and bandwidth. Fabrication routes are electron-beam lithography (lab) and deep-UV / nanoimprint (production). Sony, Metalenz, and Applied Materials are pushing pilot-line volumes; TSMC and GlobalFoundries have exploratory PDK-adjacent programmes.

Competitive landscape

Competing approaches: conventional refractive lenses (mature, cheap, no nanofab), diffractive optical elements (DOEs, established in IR/LiDAR, lower efficiency in visible), and MEMS-tunable optics (dynamic but mechanically complex). Adjacent material bets include phase-change materials (GST, GSST) for active/reconfigurable metasurfaces, and liquid-crystal-on-silicon for beam steering. Nanoimprint lithography is the key process enabler that de-risks cost.

Companies using

Connected ideas

Sources

Frontier (open questions)

• To be added.