  Stimulated Brillouin scattering (SBS) has been demonstrated in silicon
waveguides in recent years. However, due to the weak interaction between
photons and acoustic phonons in these waveguides, long interaction length is
typically necessary. Here, we experimentally show that forward stimulated
Brillouin scattering in a short interaction length of a 20 um radius silicon
microring resonator could give 1.2 dB peak gain at only 10mW coupled pump
power. The experimental results demonstrate that both optical and acoustic
modes can have efficient interaction in a short interaction length. The
observed Brillouin gain varies with coupled pump power in good agreement with
theoretical prediction. The work shows the potential of SBS in silicon for
moving the demonstrated fiber SBS applications to the integrated silicon
photonics platform.
