We present an overview of our research effort on volume holographic digital data storage. Innovations, developments, and new insights gained in the design and operation of working storage platforms, novel optical components and techniques, data coding and signal processing algorithms, systems tradeoffs, materials testing and tradeoffs, and photon-gated storage materials are summarized.

International audienceThe simultaneous existence of photonic and phononic band gaps opens up many possibilities for enhancing acousto-optical interactions at a common wavelength scale. We term such structures phoxonic crystals. By computing the existence and dependence of phoxonic band gaps on the choice of lattice and unit cell, we obtain a hierarchy of two-dimensional phoxonic crystal structures. The single-atom hexagonal and square lattices, and some multiple-atom hexagonal lattices, including honeycomb and heterometric lattices, are investigated. For definiteness, arrays of air holes in lithium niobate are considered in the computations. It is observed that decreasing the symmetry of the lattice by adding atoms of different sizes inside the unit cell leads to larger phoxonic band gaps. Examples of designs for operation at an optical wavelength of 1550 nm are given. The corresponding phononic frequencies are in the gigahertz range