We report a novel technique for storing digital optical data in coherent time-domain optical memory to circumvent the problem of coherent saturation. In this technique, the carrier frequency of a data stream to be stored is slowly chirped so its power is spread over the data bandwidth for maximum data storage. In a proof-of-concept experiment, a total of 500 bits of data were stored at a rate of 20 Mbits/s in a 45-MHz-wide channel within the inhomogeneous line of the 7F0−5D1 transition in Eu3+:Y2SiO5. The result suggests a minimum storage density of ~1.5 Gbits/cm3 for this transition. Issues related to the storage of frequency-chirped data, such as the optimum chirp width and the saturation owing to peak–sidelobe interference, are also discussed.
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