METHOD FOR REWRITING DATA IN THREE-DIMENSIONAL OPTICAL MEMORY DEVICE FABRICATED IN GLASS BY ULTRA-SHORT LIGHT PULSE

摘要

To provide a method for rewriting data in a three-dimensional optical memory element created in glass with ultrashort light pulses capable of moving created bits for rewriting. A method for rewriting data in a three-dimensional optical memory element created in glass (18) with ultrashort light pulses comprises the steps of: creating a bit (23) due to a photo-induced contrast in index of refraction inside the glass (18) in three dimensions depending of the strength of a first ultrashort-pulse laser beam; and irradiating the bit (23) created in three dimensions with a second ultrashort-pulse laser beam having a lower energy than the strength of the first ultrashort-pulse laser beam, and when condensing the laser beam with an optical lens (17), condensing the laser beam at a point shifted from the bit (23) to be moved by a predetermined distance in the opposite direction from the direction of propagation of the laser beam, thereby moving the bit (23) for rewriting.