child of Metasurfaces & Flat Optics
Physics / mechanism
A metalens is a planar metasurface engineered to perform the focusing function of a conventional curved lens. Sub-wavelength meta-atoms (typically TiO₂, GaN, or amorphous silicon pillars, 50–400 nm feature size) are patterned on a flat substrate; the local geometry of each atom imposes a phase delay on incident light, so the array as a whole imparts a hyperboloidal phase profile equivalent to a curved lens. Replaces stacked refractive elements with a single planar layer fabricated by semiconductor processes (e-beam in the lab, DUV / nanoimprint in production).
Operating regimes:
- Visible / NIR consumer: TiO₂ on glass at ~90% diffraction efficiency at 532 nm, NA up to 0.9 demonstrated in lab. Production-grade NA ~0.5.
- MWIR / LWIR: GaN-on-silicon or amorphous-Si on Si-substrate; lower efficiency tolerance, currently dominant in industrial sensing.
- UV: HfO₂ / SiO₂ candidates; mostly research-stage.
Competitive landscape
| Approach | Form factor | Volume process | Diffraction efficiency | Status |
|---|---|---|---|---|
| Refractive (curved glass / molded) | 3D stack | Injection / grinding | ~99% | Mature, cheap |
| Diffractive optical element (DOE) | Planar | Embossing / etch | 60-80% (visible) | Mature in IR |
| Metalens (TiO₂ / GaN) | Planar (single layer) | NIL or DUV | 70-90% (visible, monochromatic) | Production at consumer scale (Metalenz/ST since 2023) |
| MEMS-tunable | Planar + actuated | MEMS process | Variable | Niche |
Companies using
Connected ideas
Sources
Frontier (open questions)
See frontmatter frontier: block.