Light irradiation head and information storage apparatus

摘要

A light irradiation head of the present invention includes: a propagation body having a tapered two dimensional shape axially symmetrical to a predetermined symmetrical axis, and consisting of a first kind material that propagates electromagnetic fields of light; and a covering body covering the propagation body so as to surround the symmetrical axis, and consisting of a second kind material different from the first kind material. The propagation body further includes: a bottom edge of projecting shape or recessed shape which is present on the symmetrical axis and which is axially symmetrical to the symmetrical axis; a tip edge which is present on the symmetrical axis and which is narrow relative to the bottom edge; and a pair of reflective edges which are present on both sides of the symmetrical axis and whose interval is gradually reduced in the direction from the bottom edge side to the tip edge side.