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Magnetic Field Multiplexing in Frequency Domain Storage

IP.com Disclosure Number: IPCOM000041038D
Original Publication Date: 1987-May-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Macfarlane, RM: AUTHOR [+2]

Abstract

Optical storage density can be substantially increased by use the frequency domain. The storage process is further multiplexed in frequency domain optical storage materials by the use of an inhomogeneous Zeeman effect. This enables multiple set of holes to be burned in the same frequency range but at different values of an external magnetic field. The field itself may be homogene- ous; the inhomogeneity is provided by the sample itself, and arises because ions in different crystalline or solid-state environments may exhibit different Zeeman effects. This is typically the case for absorption bands for which the ground or excited states, or both, are non-Kramers' doublets, i.e., the ion has an even number of electrons and the site symmetry is axial or higher.

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Magnetic Field Multiplexing in Frequency Domain Storage

Optical storage density can be substantially increased by use the frequency domain. The storage process is further multiplexed in frequency domain optical storage materials by the use of an inhomogeneous Zeeman effect. This enables multiple set of holes to be burned in the same frequency range but at different values of an external magnetic field. The field itself may be homogene- ous; the inhomogeneity is provided by the sample itself, and arises because ions in different crystalline or solid-state environments may exhibit different Zeeman effects. This is typically the case for absorption bands for which the ground or excited states, or both, are non-Kramers' doublets, i.e., the ion has an even number of electrons and the site symmetry is axial or higher.

Specific illustration is made using the example of BaClF doped with divalent samarium (0.05%) in which we have demon- strated magnetic multiplexing. This material also exhibits photon gated holeburning and the ability to cycle information- containing spectral holes to room temperature without loss of the information.

The process is as follows: 1. Select a material containing a photoactive ion having an even number of electrons and sitting in a site of axial or higher symmetry, e.g., BaClF:Sm2+ . 2. Burn a set of spectral holes in a frequency region lying within the inhomogeneously broadened absorption band arising from a transition in which one of the lev...