A review of photopolymers on holography volume data storage
Jian Jialing, Cao Lin, Wei Xiqiao, Guo Jinxin, Wang Dayong, Zhang Xinping     
Institute of Information Photonics Technology and College of Applied Sciences, Beijing University of Technology, Beijing 100124, China

Overview: In this review, recent advances in photopolymer research on volume holographic storage are introduced. Volume holographic storage technology has the advantages of high storage density, huge data capacity, parallel read and write, fast transmission speed and so on. In Big Data era, this method has great potential to meet its needs of low cost and low storage density. Photopolymer has attracted more attention because of its several advantages, such as high diffraction efficiency, extreme sensitivity and high resolution. Holographic storage devices fabricated by such materials within the advantages of low cost, light weight, and high commercial value are more suitable for marketing. Since the 1990s, photopolymer materials have received extensive attention in the field of volume holographic storage. Researchers have taken various examinations to enhance the main properties of photopolymer materials such as diffraction efficiency refractive index modulation and shrinkage rate. Changing the monomer and photoinitiator types are considered as common method to satisfy different applications. By adding chain transfer agents into the photopolymer, researchers are able to control the polymer chain length to increase crosslinking density and diminish polymerization shrinkage. An another effective way to improve refractive modulation index and reduce shrinkage rate is adding different kinds of nanoparticles(such as liquid crystal, silica nanoparticles, zirconia nanoparticles, aluminum oxide nanoparticles, gold nanoparticles and so forth) to the system. The measures currently widely taken to improve the performance of photopolymers materials are the methods described above. At present, photopolymer materials have been obtained near 100% in the diffraction efficiency, more than 10-2 in the refractive modulation index, and 0.4% in the shrinkage rate. In recent years, photopolymer materials have not only attained fruitful research results on volume holographic storage, but also have achieved good development in various optical devices, such as biosensing, fiber optic communication, etc. However, there is far from large-scale commercial production. For the long-term progress of volume holographic storage, the development of photopolymer materials with excellent performance has important scientific significance and great economic benefits. Both scientific research and commercial fields need to pay more attention to photopolymer materials.

Supported by National Natural Science Foundation of China (61605006) and the Natural Science Foundation of Beijing (4182013), China