Data storage in a nanocrystalline mixture using room temperature frequency-selective and multilevel spectral hole-burning

Abstract

Persistent spectral hole-burning is shown to be suitable for multiple bit per point optical data storage at room temperature. In a novel approach employing bespoke tailoring of the effective inhomogeneous line width and line shape, by using a physical mixture of chemically different matlockite nanocrystals, a relatively broad fluorescence emission line with a top-hat distribution can be realized at the diffraction limit and at room temperature. This top-hat profile enables multiple spectral holes to be burnt, all having the same baseline. We demonstrate this with two spectral holes burnt in a diffraction limited spot, with the prospects for multihole-depth or multilevel encoding to increase the number of bits stored per spectral hole. Using thermoelectrically cooled temperatures down to 175 K, a larger number of holes is also demonstrated. The technique presented is predicted to allow for optical data densities approaching terabits/cm2 by exploiting the unique properties of these inorganic phosphors.