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Magneto Optical Light Fibers

IP.com Disclosure Number: IPCOM000091157D
Original Publication Date: 1969-Nov-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Lohmann, AW: AUTHOR

Abstract

Magneto-optic effects are very small. They are of the order of one degree Faraday rotation for practically realizable film thicknesses. Only about 1% of sensing energy in a memory is used in the detector method. The rest of the energy, however, is not useful and can be absorbed in a polarizer, for example. In this arrangement, the light has more than one opportunity to interact with a magneto-optical layer. Hence, the effect accumulates. In A, a thin fiber of glass or plastic material 1 is coated with magneto-optical material 2. Light traveling through fiber 1 bounces many times against the fiber wall. If fiber 1 is very thin, a waveguide consideration is more appropriate than bouncing of light rays. There are a variety of methods in which writing, reading, and erasing are done.

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Magneto Optical Light Fibers

Magneto-optic effects are very small. They are of the order of one degree Faraday rotation for practically realizable film thicknesses. Only about 1% of sensing energy in a memory is used in the detector method. The rest of the energy, however, is not useful and can be absorbed in a polarizer, for example. In this arrangement, the light has more than one opportunity to interact with a magneto-optical layer. Hence, the effect accumulates. In A, a thin fiber of glass or plastic material 1 is coated with magneto-optical material 2. Light traveling through fiber 1 bounces many times against the fiber wall. If fiber 1 is very thin, a waveguide consideration is more appropriate than bouncing of light rays. There are a variety of methods in which writing, reading, and erasing are done.

Curie writing by a powerful laser beam, or infrared can be done. The current I is along the fiber direction as shown. This creates a magnetization M, which is wrapped about the fiber. The direction of 1 is coupled to the rotational direction of M. Hence, there is a binary system. In an alternative, as in B, the magneto- optical material is in spirals along the fiber. The current is introduced onto the spirals around the fiber and M is longitudinal. The spiral can be coded. Again, a binary situation exists in the I and M directions.

For reading, linearly polarized light is projected into the fiber. Then, first by measuring how much of the other linear component...