Two-dimensional optical storage: high-speed read-out of a 50 GByte single-layer optical disc with a 2D format using lambda=405 nm and NA=0.85

With ever increasing storage capacities, long read-out times of content are becoming a bottleneck for the convenient use of optical storage devices. Two-dimensional optical storage (TwoDOS) is a new concept that solves this data-rate problem through parallel read-out. Furthermore, an increase of at least a factor of 2 in storage capacity is achieved by exploiting a two-dimensional format. The advantages offered by TwoDOS are obtained without the need of changing the physics of the read-out system. Using Blu-ray Disc optics, single-layered 12 cm discs with capacities up to 50 GByte have been read out successfully. Signal level and error analysis show the feasibility of a further capacity increase. Also, bit-rates as high as 700 Mbit/s during read-out have been reached. All this is achieved by applying advanced signal processing and advanced disc mastering techniques and the proper design of the optical path