All-optical, near-infrared imaging via ultra-thin structured films

https://phys.org/news/2023-05-all-optical-near-infrared-imaging-ultra-thin.html

"400–1000nm, 1000–2500nm and >2500 nm frequency bands without needing to convert light to electrons and vice-versa... concept of nonlinear metasurfaces... thin silicon film accommodates nanoscale holes... generates new color 1/3 original wavelength via 3rd harmonic generation... heating not concern... centrosymmetric material enables nonlinear silicon metasurfaces use for other third-order nonlinear interactions beyond THG... thin, inexpensive, broadband, and colorful NIR cameras and detectors"