Optical recording an or reproducing apparatus optical reproducing apparatus optical recording and or reproducing medium optical recording and or reproducing method optical recording method optical reproducing method and optical layer detection method

摘要

Signals are recorded as residual polarization in a recording and/or reproducing member, exhibiting ferroelectricity, and the difference in phase, dependent on the direction of residual polarization, of optical harmonics generated on illumination of a reproducing light beam, is detected by phase comparison with optical harmonics generated in a uniformly polarized reference member arranged in an optical path other than the optical path of the recording and/or reproducing member. Since the disclosed technique can use a conventional optical recording and/or reproducing technique, the disclosed technique is high in valuability as a multi-layered medium. The optical recording and/or reproducing layer can be readily implemented as a multi-layer structure to increase the recording capacity appreciably.