Patent ID: 6710901
Filing Date: 2004-03-23
Classification: B82Y,G03H,G11B,Y10S

Abstract:
A method for the generation of stable, volume spatially-resolved holographic data storage within a photosensitive glass sample that incurs changes of optical properties in response to two-photon absorption and heating, said method comprising:directing pulsed laser radiation at the photosensitive glass sample to induce non-optically observable changes in the glass sample; splitting of said pulsed laser radiation, prior to reaching the glass sample, into an object beam having a direct optical path of a first predetermined length and a reference beam; changing the path of said reference beam to have an indirect optical path of a second pre-determined length; focusing each of said object beam and said reference beam along said respective optical paths, to intersect at a focal volume of the glass sample, and therein to cause the two-photon absorption and primary defects in said focal volume; providing a variable time delay in said direct path of said object beam so that it reaches the focal volume of the glass sample at the same time as said reference beam; and heating of the sample to a temperature necessary and sufficient to cause the changes of optical properties due to local re-crystallization around said defects, thereby realizing the spatially-resolved writing of very high-density holograms such that about 30 different spatially-resolved holograms can be written and read in the same focal volume, thereby achieving a high density of stored information, wherein said stored information remains stable after being read.