Three-dimensional optical storage by use of an ultrafast laser

The feasibility of multilayered optical data storage is examined in glass, quartz, polycarbonate and a rhodamine B and Au (III) doped PMMA medium by using a focused 800 run, 100-fs pulsed laser. Refractive-index or fluorescent data patterns are recorded by use of an objective to focus laser pulses inside these transparent medium. The laser pulse produces a submicrometer-diameter structurally altered region in the material. For glass, quartz and polycarbonate materials, we record binary information by writing such bits in multiple planes and read it out with a microscope. We demonstrate data storage and retrieval with 0.6-mum in-plane bit spacing and 10-mum interplane spacing (100 Gbits/cm(3)). Scanning electron microscopy (SEM) are used to characterize structural changes in these materials. For the rhodamine B and Au (III) doped PMMA medium, fluorescent spectra are measured before and after laser treatment. Writing three-dimentional data bit inside the transparent medium based on a multi-photon absorption process is expected to become a useful method used to fabricate optical memory with both an ultra-high storage density and an ultra-high recording speed.