Stimulated Brillouin scattering has attracted renewed interest with the
promise of highly tailorable integration into the silicon photonics platform.
However, significant Brillouin amplification in silicon waveguides has yet to
be shown. In an effort to engineer a structure with large photon-phonon
coupling, we analyzed both forward and backward Brillouin scattering in
high-index-contrast silicon slot waveguides. The calculations predict that
gradient forces enhance the Brillouin gain in narrow slots. We estimate a
currently feasible gain of about 105W−1m−1, which
is an order of magnitude larger than in a stand-alone silicon wire. Such
efficient coupling could enable a host of Brillouin technologies on a
mass-producible silicon chip