THREE-DIMENSIONAL DIGITAL OPTICAL DATA STORAGE BY TWO-PHOTON ABSORPTION

An important way to realize super\|high density optical storage is by three\|dimensional digital optical storage based on two\|photon absorption.The rate of two\|photon excitation is proportional to the squared intensity of the incident light.This produces excitation only within a small region of the focus spot of the recording medium. The effects of two\|photon excitation,such as photopolymerization,photochromic,photobleaching and photorefractive effects,change the optical properties of the excited fraction of the recording medium.As a result,information can be written as submicrometer volume elements,and three\|dimensional digital optical data storage is achieved,the bit density of which may be as large as 10 12 Bits/cm\+3.