  We investigate the phase diagram of a dimerized Bose-Hubbard model, using
density matrix renormalization group technique. We find a new phase, which is
the coexistence of superfluid and bond-wave phases, due to the effect of
dimerization. Experimentally dimerization in optical lattice can be realized by
using two counter propagating laser beams of different wavelengths. Apart from
the conventional superfluid to Mott insulator transition, we find a new quantum
phase transition: from superfluid-bond-wave to Mott insulator-bond wave phase.
Our study suggests a rich phase diagram which can be easily probed.
