| 摘要 |
PURPOSE:To record and reproduce a micro recording bit on a magnetic recording medium, by making the length of a yoke of a ring head minute up to such degree that an area to which a light spot strikes can be secured. CONSTITUTION:Optical wave guides 8-1 and 8-3 of the single mode having the polarization plane preserving property consists of core parts 8-1a and 8-3a and clad parts 8-1b and 8-3b respectively, and a magnetic thin film 8-2 consisting of a soft magnetic material is provided on the section of the wave guide 8-1. This magnetic thin film 8-2 is slightly larger than the core part 8-1a and is ring-shaped so that a yoke part 8-2a of the magnetic thin film 8-2 is put on the whole of the section including the optical axis of the core part 8-1a, and a gap 8-2b is formed in the clad part 8-1b under the core part 8-1a. The magnetic thin film 8-2 is magnetized by the leakage magnetic field of the recording medium approximated to the place under the gap 8-2b. The polarized light from a light source 8-4 which is propagated on optical wave guides 8-1 and 8-3 has the plane of polarization rotated by the Faraday effect when it is transmitted through the magnetic thin film 8-2, and this polarized light is received through a polarizer 8-6 by a photodetector 8-7, and a signal is detected as the intensity of light. The light of only one mode can be propagated in optical wave guides 8-1 and 8-3, and thus, the light of an unnecessary mode is prevented from being noise. |
