What is "nanophotonics"

n. (context physics optics English) The science that studies the behaviour of light, and of optical devices, on a nanometre scale.

Nanophotonics or Nano-optics is the study of the behavior of light on the nanometer scale, and of the interaction of nanometer-scale objects with light. It is a branch of optics, optical engineering, electrical engineering, and nanotechnology. It often (but not exclusively) involves metallic components, which can transport and focus light via surface plasmon polaritons.

The term "nano-optics", just like the term "optics", usually concerns ultraviolet, visible, and near-infrared light (free-space wavelength around 300-1200 nanometers).