Sub-Terabyte-Data-Capacity Optical Discs Realized by Three-Dimensional Pit Selection

To realize optical discs with the sub-terabyte data capacity, we propose the three-dimensional pit selection (3DPS) method where a single data pit to be read out in a multi-layer disc is selected three-dimensionally to obtain super-resolution in the disc plane and to reduce layer cross-talk. To examine the feasibility of this method, the phase-change pit capsule method was tested where the data pits consist of a phase-change material which melts during readout. The super-resolution effect was observed for both layers of a dual-layer disc. It was shown that a quadric-layer disc can be designed because of the high transmittance of each layer. Thus, 3DPS is considered to have the potential for a data capacity of hundreds of gigabytes with a conventional optical system.