Two-photon energy transfer enhanced three-dimensional optical memory in quantum-dot and azo-dye doped polymers

A three-dimensional bit-by-bit optical memory system in quantum-dot and azo-dye doped polymers is demonstrated in this paper. It is shown that two-photon absorption can be used to excite resonance energy transfer from luminescent CdS quantum dots to azo-dye molecules. As a result, the isomerization of azo-dye molecules leads to a pronounced refractive index change. This two-photon-excited energy transfer process in the quantum-dot and azo-dye polymer not only allows for high efficient multilayer information recording into the volume of thick samples but also offers a refractive index window for readout.