Patent ID: 8149653

Claim:
A light source unit that is to be joined to a slider to form a thermally-assisted magnetic recording head, the slider including an optical system formed in an element-integration surface of a slider substrate and configured to propagate a light for thermal assist, the light source unit comprising: a unit substrate comprising: a joining surface that faces the slider substrate when the unit substrate is bonded to the slider; and a source-installation surface adjacent to the joining surface; a light source provided in the source-installation surface and emitting the light for thermal assist that is to be entered into the optical system; and a photodetector configured to measure an output from the light source for adjusting the output, bonded to a rear joining surface of the unit substrate that is on the side opposite to the joining surface in such a manner that a rear light-emission center of the light source on the side opposite to a light-emission center from which the light for thermal assist is emitted is covered with a light-receiving surface of the photodetector.