New development of multilayered optical memory for terabyte data storage

We report a recording medium in which a three-dimensional nanoscale structure can be photofabricated for multilayered optical memory using two-photon process. By fabricating the structures in the medium, we can control the shape of the recorded bits and in effect, their spatial frequency distribution. We succeeded in recording bits with 0.5 μm interval in any particular plane and 2.0 μm interval between successive layers. Thus, a storage density of 2.0 Tb/cm³ is achieved.