Page "Microphotonics" Paragraph 1

Microphotonics employs at least two different materials with a large differential index of refraction to squeeze the light down to a small size.

Generally speaking virtually all of microphotonics relies on Fresnel reflection to guide the light.

If the photons reside mainly in the higher index material, the confinement is due to total internal reflection.

If the confinement is due many distributed Fresnel reflections, the device is termed a photonic crystal.

There are many different types of geometries used in microphotonics including optical waveguides, optical microcavities, and Arrayed waveguide gratings.