248-Bit optical data storage in Eu(3+):YAlO(3) by accumulated photon echoes

The successful storage and retrieval of 248-bit temporal optical data in Eu(3+):YAlO(3) by accumulated photon echoes is reported. Owing to the long storage time of this crystal, the input data can be written bit by bit by quickly varying the separation of two laser pulses, while the stored data are recalled simultaneously after some storage period, which extends up to a few hours. The maximum data length, previously thought to be limited by the optical dephasing time T(2), has been found to be four times shorter than T(2) and attributable to spectral diffusion.