Experimental study on three dimensional optical data storage in LiF: F₂

Based on the conversion of F₂ centers to F₃⁺ centers using IR pulse laser in LiF : F₂ crystal and the difference of fluorescence spectrum in the two centers, the principle experiment of three dimensional optical data storage was realized using multi-photons absorption writing technique and fluorescence confocal reflection readout. Using NA 0. 68 objective to focus on chirped amplified femtosecond laser pulse at 800 nm, 100 fs, 1 kHz inside LiF : F₂ crystal, writing in 3D was done successfully by moving crystal; fast and non-destroy reflectional confocal data reading was operated by using 405 nm blue laser and detecting 540 nm fluorescence produced by F₃⁺ centers. Compared with transmission confocal dispersion and phase contract read-out, this optical setup can be compatible with existent optical disc technology, and the structure is simple. The most important thing is that information recorded depends on the change of fluorescence rather than that of refractive index, so it is potential to achieve hundreds of layers readout.