In big data era, there is a higher demand for long lifetime and low cost storage of massive data. However, the current main methods of data storage, such as disk, tape and solid-state hard disk, have remain many problems, such as high maintenance cost, high power consumption, low recording density, short storage time, slow reading speed and so on. Faced with such a huge amount of data storage, the current storage methods gradually reveal the problems in the aspects of low cost and long lifetime. A new storage technology is urgently needed to make up for the shortcomings of existing storage methods.

The traditional optical data storage technologies, like CD, DVD and BD, have the advantages of low cost and long lifetime when maintaining data. They had been widely used in every household since 1980s. But in recent years, the optical data storage market, which has experienced several generations of progress, has gradually become depressed due to the improvement of network transmission speed. Facing the demand of long-lifetime and low cost storage in the era, the spring of optical data storage is come back. Recently, the traditional optical data storage technology has been widely used in the data storage industry. Some new optical storage technologies, such as holography, multi-dimensional variables and super-resolution, are also gradually improving and developing, some of which are close to industrialization. The various optical storage technologies are reviewed by “Development status and prospect of optical storage technology”. In the field of the holographic data storage, " Optical holographic data storage—The time for new development " summarizes the evolution and current status of the technologies. “Phase modulated collinear holographic storage” summarizes the effective methods of holographic optical storage to increase recording density by adding one-dimensional phase modulation variable. “Review on polarization holography for high density storage” introduces the use of polarization, one-dimensional modulation variable, further improves the recording density of holographic data storage. “A review of photopolymers on holography volume data storage” focuses on the review of the research status and future development trend of holographic storage materials. Instead of increasing the modulation dimension by phase and polarization in holographic data storage, the five-dimensional modulation modes of three-dimensional space, wavelength and polarization can be understood through two papers: “Encoding disorder gold nanorods for multi-dimensional optical data storage based on” and “Dimension expansion of high-capacity optical data storage”. In addition, the technology of super-resolution optical data storage using two beams is also a hotspot in recent years. “Research progress of super-resolution optical data storage” and “Industrialization oriented technology of dual-beam super-resolution data storage” are two representative papers in this field. Finally, we have selected four research papers: “An integrated cyber-physical system for automatic identification of massive discs” which introduces the system of automatic identification for batch optical disc in data storage system. “Error correction methodology based on redundant recovery code for optical storage system” which introduces a method of error correction and recovery for data stored in BD. “Monitoring and optimization of the synthesis process of the holographic doped photopolymers” which introduces the analytical methods of popular doped photopolymer in recent years. The new development of magneto-optical data storage is introduced in the study of “Microscopic three-temperature model for all-optical switching in GdFeCo” which enables faster calculations of the heat-induced magnetization dynamics in magneto-optical materials with large areas.. 

We hope the special issue of “Optical data storage technology and its future” can serve as a trigger, through reviewing the foundation of the core technology supporting the development of optical data storage technologies at present, showing innovative optical data storage technologies and discussing the development trend of future optical data storage technologies, so as to make a contribution to the research of physical mechanism of future optical data storage technologies and the development of corresponding storage materials for the majority of colleagues. Innovation of our traditional concepts of data storage cognition will bring new progress to the development of optical data storage. Promote the renewal of this old technology, developing new data storage market, and ensure that our data wealth can be preserved for a long time and safely.

Finally, it should be pointed out that the opinions on technology evaluation and future prediction in the papers belong to the author's personal perception, and do not represent the views of the editors of this special issue.