Optical element

摘要

An optical element according to the invention uses a thin film-like two-dimensional photonic crystal having a structure of periodic repetition in two directions perpendicular to each other. When the two periodic directions are Y-axis and Z-axis directions, opposite surfaces of the photonic crystal structure perpendicular to the Z-axis direction and parallel to the Y-axis direction are used as a light input surface and a light output surface respectively. The direction of movement of light rays incident onto the light input surface is decided so that it is parallel to the YZ plane and inclined at a predetermined inclination angle to the Z-axis direction.