Frequency-shifted light storage via stimulated Brillouin scattering in optical fibers

A method for storing optical data pulse sequences, frequency shifted with respect to the original data pulse frequency, is theoretically described and experimentally demonstrated. Data pulses are converted into long-living acoustic waves via stimulated Brillouin scattering in optical fiber by counterpropagating write pulses of one frequency, and later they are retrieved by read pulses at a different frequency giving rise to frequency-shifted stored pulses. The shifted frequency is governed by the phase-matching condition between the read pulse and the acoustic wave, which can be satisfied using birefringent fibers. The converted frequency is +/-52 GHz and is tuned by applying strain to the fiber with a slope coefficient of +/-1.8 MHz/micro epsilon, and conversion efficiency can be as high as 13% for the storage time of 8-25 ns.