  Stimulated Brillouin scattering (SBS) is a very fundamental interaction
between light and travelling acoustic waves, which is mainly attributed to the
electrostriction and photoelastic effects with the interaction strength being
orders of magnitude larger than other nonlinearities. Although various photonic
applications for all-optical light controlling based on SBS have been achieved
in optical fiber and waveguides, the coherent light-acoustic interaction
remains a challenge. Here, we experimentally demonstrated the Brillouin
scattering induced transparency (BSIT) in a high quality optical
microresonantor. Benefited from the triple-resonance in the whispering gallery
cavity, the photon-phonon interaction is enhanced, and enables the light
storage to the phonon, which has lifetime up to 10us. In addition, due to the
phase matching condition, the stored circulating acoustic phonon can only
interact with certain direction light, which leads to non-reciprocal light
storage and retrieval. Our work paves the way towards the low power consumption
integrated all-optical switching, isolator and circulator, as well as quantum
memory.
