MULTIFREQUENCY 3-DIMENSIONAL OPTICAL READ-ONLY MEMORY DISKS USING METALLIC ISLAND FILMS - PRELIMINARY EXPERIMENTS

Basic operation of new multifrequency three-dimensional (3-D) optical read-only memory (ROM) disks has been demonstrated experimentally. Several types of metallic island film exhibiting a selective resonance absorption in a visible-near infrared region are used as recording layers on the 3-D disks. The monochromatic light with a suitable wavelength near the resonance wavelength of each layer is used for the readout of information. We demonstrate that bar-code patterns recorded in silver and copper island layers can be read by using transmitted or reflected light. Furthermore, we also show that the 3-D disks with greater-than-or-equal-to 3 recording layers can be realized.