Two-photon-induced three-dimensional optical data storage in CdS quantum-dot doped photopolymer

The authors demonstrate three-dimensional erasable bit optical data storage in a quantum-dot doped photopolymer under two-photon excitation by a near-infrared femtosecond pulsed laser beam. It is shown that the photorefractive polymer consisting of poly(vinyl carbazole), ethyl carbazole, 4-(diethylaminobenzylidene)-malononitrile, and CdS quantum dots exhibits the changes not only in refractive index but also in fluorescence. Such a photosensitivity provides a multimode readout mechanism. In particular, the use of S rich surface quantum dots not only allows the two-photon-induced bit optical data storage with greater contrast but also expands the margin between permanent and erasable recording thresholds.