Single beam Two-photon recording and one-photon fluorescent reading three-dimensional optical data storage system

摘要

A scheme of three-dimensional optical data storage based on single-beam femotsecond (fs) laser two-photon recording and one-photon fluorescent readout has been developed. A mode-locked Ti: sapphire fs laser beam of pulse width 80fs at a repetition rate of 80MHz and a wavelength of 800nm was used for two-photon recording and a CW laser with a wavelength of 532nm was used for one-photon fluorescent readout. Thus, data bits can be recorded and retrieved inside a photochromic molecule doped polymethylmethacrylate (PMMA) storage medium. With a 0.65 NA objective used for recording and readout, the effects of writing power and exposure time on the spatial resolution of the system were explored. Bit sizes were observed to increase exponentially in size with excitation power and linearly in size with exposure time approximately. The multilayer capability of the system for three-dimensional optical memory was demonstrated and experimental results of eight-layer data inside a diarylethene derivative doped PMMA storage medium were presented.