Is it possible to store 100ps-long optical pulses into acoustic waves? The question is very justified as the resonance that we use for light-storage is only 30 MHz wide. We now demonstrated in our recent paper in npj nanophotonics, that relatively short pulses with a broad bandwidth up to several GHz can be stored into traveling sound waves and retrieved over 100 pulse widths.

Title: Brillouin light storage for 100 pulse widths

Authors: Birgit Stiller, Kevin Jaksch, Johannes Piotrowski, Moritz Merklein, Mikołaj K. Schmidt, Khu Vu, Pan Ma, Stephen Madden, Michael J. Steel, Christopher G. Poulton, and Benjamin J. Eggleton

Abstract:

Signal processing based on stimulated Brillouin scattering (SBS) is limited by the narrow linewidth of the optoacoustic response, which confines many Brillouin applications to continuous wave signals or optical pulses longer than several nanoseconds. In this work, we experimentally demonstrate Brillouin
interactions at the 150 ps time scale and a delay for a record 15 ns which corresponds to a delay of 100 pulse widths. This breakthrough experimental result was enabled by the high local gain of the chalcogenide waveguides as the optoacoustic interaction length reduces with pulse width. We successfully transfer 150 ps-long pulses to traveling acoustic waves within a Brillouin-based memory setup. The information encoded in the optical pulses is stored for 15 ns in the acoustic field. We show the retrieval of eight amplitude levels, multiple consecutive pulses, and low distortion in pulse shape. The extension of Brillouin-based storage to the ultra-short pulse regime is an important step for the realization of practical Brillouin-based delay lines and other optical processing applications.