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Magnetic Recording with Laser Beams

IP.com Disclosure Number: IPCOM000094952D
Original Publication Date: 1965-Jul-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Freiser, MJ: AUTHOR [+2]

Abstract

The arrangement accomplishes magnetic recording using laser beams. The state of magnetization of a ferromagnetic medium can be changed by impinging a laser light pulse upon the medium. Since circularly polarized light possesses angular momentum in the direction of propagation of the light, such angular momentum can be transferred from the light to the magnetic spin system of the ferromagnetic medium. This form of transfer can be employed as a recording of information. Light pulse 2 impinges upon polarizer 4 so that the light 2' passing through polarizer 4 impinges upon transparent ferromagnetic medium or film 6. The latter's magnetization vector M is at 45 degrees to the polarized light beam 2'.

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Magnetic Recording with Laser Beams

The arrangement accomplishes magnetic recording using laser beams. The state of magnetization of a ferromagnetic medium can be changed by impinging a laser light pulse upon the medium. Since circularly polarized light possesses angular momentum in the direction of propagation of the light, such angular momentum can be transferred from the light to the magnetic spin system of the ferromagnetic medium. This form of transfer can be employed as a recording of information. Light pulse 2 impinges upon polarizer 4 so that the light 2' passing through polarizer 4 impinges upon transparent ferromagnetic medium or film 6. The latter's magnetization vector M is at 45 degrees to the polarized light beam 2'. When the angular momentum of the polarized light 2' is transferred to medium 6, the magnetization vector M is tilted out of the plane of 6, such tilting creating an internal demagnetization field. The magnetization of medium 6 processes about this demagnetization field so that for a light pulse 2 of appropriate duration, the final state of medium 6 is one in which the magnetization is reversed from its initial state. Vector M' could represent the storage of a binary 1 and vector M could represent the storage of a binary 0.

Medium 6 is composed of europium oxide. When the initial beam of plane polarized light 2 impinges on medium 6 with its direction of polarization at 45 degrees to that of vector M, such light is resolved into a polariz...