Three-dimensional memory system based on two-photon absorption

We discuss a volume optical storage, a 3D memory based on two-photon absorption process. This memory has an advantage over a 2-D memory in that it combines fast access time together with high memory capacity - a capability that 2- D memories cannot deliver. Two-photon 3D memory allows the data to be accessed in parallel, and thus speeds up data transfer rate significantly. In this paper, we address the issue of memory hierarchy which has been organized to provide a performance continuum of different memory technologies available at present. We justify the two-photon 3-D memory as a viable technology to fill the performance gap currently exists between a primary and secondary siorage systems. We also discuss the system capacity pertaining to two unique addressing schemes, i.e., orthogonal beam addressing and counterpropagating beam addressing. Finally, we report the progress in system study regarding the effect of memory material characteristic to the system design and development. Factors such as optimum wavelengths for read/write operations, material fluorescence, material fatigue, and the concentration of active molecules in the host material were considered.