  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 150ps-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 realisation of practical Brillouin-based delay lines and other optical
processing applications.
