We report the one-step precipitation of CdS quantum dots in the volume of CdS-doped silicate glass under the focused femtosecond laser beam without additional heat treatment of glass. Femtosecond direct laser writing leads to the annular distribution of the precipitated CdS quantum dots in laser-written domain optical properties of which could be tuned by laser beam parameters. Increasing the laser pulse number to 10 significantly enhances luminescence intensity in the domains, while further increasing up to 10 pulses leads to luminescence quenching. A possible scenario for the formation and distribution of quantum dots is proposed.

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Optical data writing and rewriting with a 10.8 GB/cm3 capacity based on the formation of luminescent silver nanoclusters inside silver-doped sodium aluminoborate glass by ultrafast laser pulses are demonstrated. Even a single laser pulse with an energy of only 60 nJ enables writing a submicron-sized domain yielding a well-detectable photoluminescence signal due to laser-induced silver nanoclustering. We showed the possibility of reducing the distance between luminescent domains to 0.6 μm, which does not affect the reliable readout and multilayer capabilities of optical data storage. The investigation of the thermal stability of laser-written domains showed that they could survive at temperatures up to the glass transition point. Thermal annealing of glass with the recorded data has been shown to erase the information together with the laser-written domains. The possibility of subsequent rewriting of new data is also confirmed. Single-pulse laser-induced nanoclustering paves the way to fast and ultradense 3D data writing in glass media for robust long-lasting rewritable data storage based on luminescent nanomaterials.

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Multidimensional data recording inside nanoporous high-silica glass by a femtosecond laser beam has been investigated. It is shown that three femtosecond laser pulses at pulse repetition rates up to 1 MHz are sufficient for recording 3 bits of information inside nanoporous glass, which is an order of magnitude lower than the number of pulses required for data writing in silica glass and provides a corresponding gain in the data writing speed. Multilayer data recording and reading were demonstrated providing the storage density corresponding to the capacity of 25 GB in the optical compact disc form factor. An outstanding thermal stability of the proposed optical data storage is confirmed by the 24 h long heat treatment at 700°C, which could not damage the recorded data.