Patent ID: 6897433
Filing Date: 2005-05-24
Classification: G11B,G11C

Abstract:
1. A method for rewriting data in a three-dimensional optical memory element created in glass with ultrashort light pulses, comprising the steps of: (a) creating bits due to a photo-induced contrast in index of refraction inside the glass in three dimensions by a strength of a first ultrashort-pulse laser beam; and (b) irradiating the bits created in three dimensions with a second ultrashort-pulse laser beam having a lower energy than the strength of said first ultrashort-pulse laser beam, and when condensing the second ultrashort-pulse laser beam with an optical lens, condensing the second ultrashort-pulse laser beam at a point shifted from the bits to be moved by a predetermined distance in an opposite direction from the direction of propagation of the first and second ultrashort-pulse laser beams, thereby transferring the bit for rewriting.