LIGHT IRRADIATION HEAD AND INFORMATION STORAGE DEVICE

摘要

A light irradiation head having a structure for propagating light from a light source efficiently, and an information storage device capable of high-density recording using such a light irradiation head. The light irradiation head comprises a propagation body made of a class 1 material propagating the electromagnetic field of light having tapered two-dimensional shape line symmetric to a specified axis of symmetry, and a body made of a class 2 material different from the class 1 material covering the propagation body to surround the axis of symmetry. The propagation body has a protruding or recessed bottom edge existing on the axis of symmetry line symmetrically thereto, a forward edge narrower than the bottom edge existing on the axis of symmetry, and a pair of reflection edges existing on the opposite sides of the axis of symmetry while decreasing the interval gradually from the bottom edge side toward the forward edge side.