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Optical Storage System with Luminescent Read-Out

IP.com Disclosure Number: IPCOM000115601D
Original Publication Date: 1995-May-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 58K

Publishing Venue

IBM

Related People

Brady, MJ: AUTHOR [+2]

Abstract

Presently, all existing "optical" data storage systems use some form of thermal writing. That is, data is written by heating, to burn a hole, or melt and amorphize a spot, or thermomagnetically switch a magnetic domain. These processes require thermal input from lasers on the order of 20 to 40 millWatts in order to produce the changes in the physical or chemical structure of the materials to perform the write/erase function. The data read out in these optical systems is passive: Some change in the optical properties of the medium, such as reflectivity, is used to define a binary bit.

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Optical Storage System with Luminescent Read-Out

      Presently, all existing "optical" data storage systems use some
form of thermal writing.  That is, data is written by heating, to
burn a hole, or melt and amorphize a spot, or thermomagnetically
switch a magnetic domain.  These processes require thermal input from
lasers on the order of 20 to 40 millWatts in order to produce the
changes in the physical or chemical structure of the materials to
perform the write/erase function.  The data read out in these optical
systems is passive: Some change in the optical properties of the
medium, such as reflectivity, is used to define a binary bit.

      Disclosed is a class of optical storage devices in which
photoexcitation is used to write the information, and stimulated
luminescence is used for data readout.  The technique utilizes the
phenomenon of electron trapping in a class of materials of the
alkaline earth crystals, doped with rare earth elements [1,2].
Proper choice of dopants, or activators in a system such as Zinc
Sulfide, for example, allows writing to be accomplished at one
wavelength, and reading at a different wavelength, by means of
electroluninescence, thermoluninescence, or photoluninescence.  The
head would contain two lasers: a short wavelength laser, (400 to 600
nm), to excite carriers, and a longer wavelength laser ( 800 to 1000
nm) to lower the carriers to the ground state.  These processes
require relatively low power lasers when compared to...