Photochromic 3D Optical Storage: Laser‐Induced Regulation of Localized Optical Basicity of Glass

Abstract 3D optical storage, spatially expanding storage capacity, is regarded as an effective and economical way to break the diffraction limit of the conventional 2D optical storage. In this study, a new kind of 3D optical storage medium, i.e., vanadium ions (V 5+ ) doped sodium borate glass, is developed, showing intriguing spatially‐selected photochromism (PC) upon laser driven excitation. Significantly, a brand‐new PC mechanism of V 5+ ‐aggregation regulated by localized optical basicity (OB) of glass is proposed and demonstrated. The developed PC glass is responsive to a low‐price desktop‐level mini‐laser to encode optical information, yields unique twofold decoding modes in bright‐ and dark‐fields, and shows good data erasibility. 3D volumetric optical storage with a memory density of ≈480 Mbit cm −3 is realized with the aid of an advanced femtosecond laser micro‐machining system. The findings suggest a novel design approach to fabricate 3D PC glass in terms of manipulating the scale of optical basicity in glass, hopefully stimulating the development of new multi‐dimensional PC optical storage media.