Toward non-volatile photonic memory: concept, material and design

Digital technology is one of the greatest modern breakthroughs, allowing sounds, words and images to be stored in binary form. However, there is a huge gap between the amount of data created daily and the capacities of existing storage media. Developing multibit memory in which 2(n) levels, typically represented by distinguishable current levels, can be achieved in a single cell is a critical specification for achieving high-density memory devices. Compared with electrically operated memory, photonic memoryin which electrical read-out is orthogonal to the photo-programming operationpromises high differentiation among different data levels. From another aspect, benefiting from its high density, multifunctionality, low power consumption, and multilevel data storage, photonic memory devices hold future promise for built-in, non-volatile memory and reconstructed logic operation and are expected to bridge this capacity gap. Thus, we present a review on the development of photonic memory, with a view towards inspiring more intriguing ideas on the elegant selection of materials and design of novel device structures that may finally induce major progress in the manufacture and application of photonic memory.