Voltage-tunable optical data storage using persistent spectral hole burning

The use of persistent spectral hole burning in optical data storage allows an increase of the storage density up to a factor of 1000 compared to the common spatial matrix of optical bits.1 The information is stored by burning at low temperature a sequence of narrow spectral holes in the inhomogeneously broadened optical transition of optical centers, e.g. dye molecules embedded in an amorphous polymer, with a tunable narrow-bandwidth laser. One bit of information is encoded by the presence or absence of a hole at a given location in frequency space. The information is read by observing the absorption or the fluorescence of the storage material using a laser with tunable frequency. One of the problems of spectral hole burning data storage arises from the fact that for addressing the memory locations the laser frequency has to be changed over a large frequency range with high accuracy and speed.