ABSTRACT
The ever-increasing demand for more storage capacity has compelled ongoing technical innovation in information storage, motivating the extension of conventional two-dimensional surface storage techniques to three-dimensional volumetric storage. Such ultra-high density volumetric optical data storage has been well heralded as a key for the next generation information storage techniques. These techniques have received tremendous research and development efforts to improve both storage capacity and system performance over the last two decades. This entry introduces three main variants of volumetric storage: holographic, bit-by-bit, and multi-dimensional storage. The fundamental principles, material requirements and system developments of these three high-density volumetric storage approaches are summarized. The advantages of each technique as well as the challenges for the future development are described, and research directions which may lead to breakthroughs in ultra-high density techniques are discussed.
