The holographic optical storage method stores information in a three-dimensional space of the recording medium, and writes and reads it in parallel with two-dimensional data transmission. Therefore, it features large capacity and high speed that traditional optical discs cannot match. As early as the 1960s, this method was hailed as a high-density and high-speed data storage method. However, due to the lack of good recording materials at that time, it only remained in conceptual research and did not develop well. Throughout the development history of holographic optical storage, every major progress depends on the materials. In the 1990s, people employed the photorefractive effect of crystals to carry out volume holographic data storage, which once became a research hotspot with many ingenious designs being proposed. AT&T, Bell lab, IBM, RCA, and 3M in the USA, Thompson CSF in the UK, NEC and Hitachi production institute in Japan, and California Institute of Technology and Stanford University in the USA have attempted to study holographic optical storage.

After entering the 21st century, companies represented by InPhase and Aprilis in the USA proposed photopolymer as a holographic optical storage material, with a data storage life of up to 50 years. Japan's Optware company has taken a significant step towards the productization of holographic optical storage technology with its unique collinear holographic optical storage method which can effectively avoid interference from environmental vibrations. However, there is still a significant gap between the actual recording density and the theoretical value of holographic optical storage technology. The reason is that there are too few parameters available for modulation in traditional holographic optical storage technologies. Using various parameters of light for multi-dimensional modulation, the recording density of holographic optical storage can be further improved to fully utilize the original capabilities of holographic optical storage. However, how to record and read multi-dimensional modulation information of light is a challenge.

In China, in the 1990s, Beijing University of Technology developed a high-capacity disk holographic data storage system by employing crystal materials as the recording medium, which realized non-volatile storage and a volume storage density of 10 Gb/cm³. Tsinghua University constructed an orthogonal polarization dual channel access system and a large capacity volume holographic correlation system in 2006 and 2009 respectively.

Since 2012, we have carried out research on holographic data storage at Beijing Institute of Technology, proposed to increase the phase and polarization modulation modes, and adopted multi-dimensional modulation holographic optical storage technology, which can not only improve the storage density but also accelerate the data transmission rate. Additionally, we have also researched the polarized holography theory based on tensor models for polarization modulation, and our achievements take the lead among peers in the world. Based on previous studies, we have researched polarization-sensitive composite holographic recording materials. By introducing new photosensitizers and composite substrate benzyl methacrylate, the polarization response performance of the materials has been improved to some extent, thereby providing a theoretical and technical basis for preparing high-performance multi-dimensional response materials.

At present, our research on utilizing multi-dimensional modulation to improve holographic data storage performance is among the international advanced levels, and these achievements are closely related to the study we conducted during our time at the School of Optics and Photonics at Beijing Institute of Technology. We will introduce our series of research on this technology during this period and would like to provide our paper as a tribute to the 70th anniversary of the establishment of the School of Optics and Photonics at Beijing Institute of Technology.

Multi-dimensional modulation holographic data storage technology maximizes the ability of holography to store the amplitude, phase, and polarization information of light. While effectively enhancing the recording density of holographic data storage, it can also improve the data transmission speed. However, the influence of reconstruction noise on the density of holographic data storage should be fundamentally overcome to narrow the gap between the actual holographic data storage density and the theoretical value. Further research on multi-dimensional modulation high-density holographic data storage technology is also necessary to develop photopolymer holographic data storage materials with China's independent intellectual property rights, especially polarized holographic materials that can simultaneously record the amplitude, phase, and polarization information of light. We are convinced that with the further study of polarized holographic tensor theory and deep learning application, innovative achievements in multi-dimensional modulation, deep learning fast reading, and composite materials continue to be made. In addition, a new era of multi-dimensional modulation holographic data storage technology research will be ushered in soon. With the further development of industrialization research on holographic data storage technology, our country can seize the commanding heights of optical storage intellectual property rights and standards, and promote the formation of a new optical storage industry oriented to big data archiving and storage.

In addition to holographic data storage technology, glass storage is also one of the deployed long-term cold data storage technology schemes, while DNA data storage is more in the theoretical stage. In terms of traditional technology, if solid-state disks can break through long-term power outage data storage and further reduce data storage costs, they will have broader applications in cold data storage. Traditional Blu-ray discs can make breakthroughs in multi-layer writing, but the process is difficult. If they have a high yield rate, they can still alleviate the data storage pressure in the short term. At present, a data storage model with integrated magneto optoelectronic technology has been built, and more technological upgrading and new technologies will gradually be proposed to jointly solve the storage problem of explosive big data growth.