Browse Prior Art Database

Method to Increase Readback Signal-To-Noise Ratio From Optical Disk

IP.com Disclosure Number: IPCOM000035345D
Original Publication Date: 1989-Jul-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Jipson, V: AUTHOR [+3]

Abstract

Described herein is a layered disk structure for optical storage which increases the signal-to-noise ratio for shot noise limited media without significantly increasing the required data recording laser power. A heat sink layer is provided which desensitizes the media and allows more readback photons to be incident on the disk without erasing the recorded data. The heat sink is partially thermally isolated from the recording layer to reduce the effect of the heat sink during data recording pulses, which are shorter than reading pulses.

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Method to Increase Readback Signal-To-Noise Ratio From Optical Disk

Described herein is a layered disk structure for optical storage which increases the signal-to-noise ratio for shot noise limited media without significantly increasing the required data recording laser power. A heat sink layer is provided which desensitizes the media and allows more readback photons to be incident on the disk without erasing the recorded data. The heat sink is partially thermally isolated from the recording layer to reduce the effect of the heat sink during data recording pulses, which are shorter than reading pulses.

In the figure, the optical disk structure is illustrated. It consists of a recording layer separated from a highly thermally conductive heat sink layer 2 by a thermal buffer layer 3. The thickness x of buffer layer 3 is chosen such that much of the heat generated by the read laser pulse is conducted to heat sink layer 2. Buffer layer 3 is thick enough that much of the heat from the shorter data recording pulse does not have adequate time to reach heat sink layer 2. There is an optimum thickness x of buffer layer 3 dictated by the particular pulse widths for recording and reading and the thermal properties of the individual materials comprising the disk structure.

Detailed modelling of the heating of this type of optimized structure as a function of buffer layer thickness was performed. The active layer 1 was chosen to be magneto-optic (e.g., TbFeCo), although phase...