The present invention relates to a high-speed optical memory element. In
order to increase speed of a memory element, optical pulse is recorded
and read all-optically without conversion into electrical signal at very
high speed. Optically-induced spin accumulation is used for recording the
ferromagnetic metal embedded into optical waveguide operates as a high
speed memory element. The ferromagnetic metal is sandwiched between a
conductor on one side and a tunnel barrier followed by a conductor on the
other side. The voltage is applied between two conductors. For data
recording, the optically induced spin-polarized tunneling and spin
accumulation is used. The optically induced spin-polarized tunneling
occurs due to absorption of circularly polarized light. The torque of
accumulated spin reverses magnetization of ferromagnetic metal. For
reading Faraday rotation or non-reciprocal loss/gain in
semiconductor-ferromagnetic-metal hybrid is used.