US Patent 7932527 Light-emitting device and illuminator

A light-emitting device, having high light extraction efficiency, capable of obtaining diffused light is obtained. This light-emitting device comprises a light-emitting diode, a portion, formed on a plane substantially parallel to a light-emitting surface of the light-emitting diode, having a dielectric constant periodically modulated with respect to the in-plane direction of the plane substantially parallel to the light-emitting surface and a member provided on the side of the light-emitting surface of the light-emitting diode for diffusing light emitted from the light-emitting diode.