A team from the University of Shanghai for Science and Technology develops single-beam multi-dimensional optical storage technology to achieve Pb-level storage capacity

China News Service, Shanghai, September 29 (Reporter Xu Jing) The team of Professors Gu Min and Professor Zhang Qiming from the School of Intelligent Technology of the University of Shanghai for Science and Technology independently developed single-beam multi-dimensional optical storage technology, which enables a single three-dimensional storage point to distinguish 1024 states, corresponding to 10 bit information capacity, and achieves high-speed writing and wide-field parallel reading. The theoretical storage capacity of DVD-sized media can reach approximately 0.4 Pb, and the data reading reliability exceeds 99.99%.

The innovative results were published in the international academic journal "Nature Photonics" on the 29th.

"In traditional binary storage, a recording unit usually only has two states of '0' and '1', but our technology allows a recording unit to have 1024 distinguishable states." Zhang Qiming explained, "In the past, multiple recording units were required to carry information together, and now it can be completed by increasing the information capacity of a single recording point. In this way, increasing the capacity of optical storage no longer only relies on continuously shrinking the recording points or increasing the number of storage layers, but can also open up new space by allowing 'one point to store more information'."

An 8K Ultra HD image contains approximately 33 million pixels. Taking an 8-bit grayscale image as an example, one pixel has 256 grayscale values. If each storage unit can only record "0" or "1", 8 such units are needed to store the grayscale information of one pixel; and if a recording point can distinguish 1024 states, it can carry 10 bits of information. In other words, after a 10-bit storage point completes the storage of the original 8-bit grayscale information, the extra 2-bit information can also provide additional coding space for in-situ optical artificial intelligence training. In the future, if information recording and optical computing functions are combined, so that the same unit has both storage and computing capabilities, it is expected to achieve "zero-distance storage and computing integration."

To achieve Pb-level ultra-high-density optical storage, traditional super-resolution technology routes often require two beams of light to work together to complete writing and reading, which brings about system problems such as precise registration and stable control. This time, the team used a single beam of monochromatic light to complete writing and reading respectively, overcoming the system problems caused by the complex dual-beam collaboration in Pb-level ultra-high-density storage, and breaking the dependence of high-capacity optical storage on dual-beam read and write architecture. On this basis, high-speed scanning and writing and wide-field parallel reading further increase data throughput, opening up new technical space for high-speed, integrated and large-scale applications of Pb-level and even larger-capacity optical storage.

Extending from 8K images to artificial intelligence training data, scientific research data and medical imaging, the scale of cold data will continue to grow. Faced with this kind of massive information, storage capacity should not only be measured by “how much it can be stored,” but also by how the capacity is obtained and whether the data can be accessed efficiently. The team introduced grayscale into a new information dimension, enabling a single recording point to carry 10 bits of information. The capacity improvement expanded from "increasing the number of recording points" to "increasing the amount of information at each recording point." Pb-level or even higher capacity is the result of the further expansion of this multi-dimensional information carrying capacity. On the basis of the existing 0.4 Pb, if the layer spacing is further compressed from 5 μm to 1 μm, and the gray-scale encoding is expanded to 10,000 levels, the theoretical capacity is expected to increase to approximately 20 Pb. Combined with single-beam reading and writing and high-speed parallel access, this technology also provides a new technical path for high-capacity and high-throughput storage of massive cold data.

Gu Min said: "Facing the future of massive data storage, Pb capacity is not the only measurement indicator. To truly move towards application, it must not only be able to carry more information, but also take into account the reading and writing speed, system complexity and device integration capabilities. This research has expanded the development path of optical storage from both the information dimension and the reading and writing architecture, creating conditions for Pb-level and even higher-capacity optical storage to further move towards engineering and industrialization."