  Synchronization is of great scientific interest due to the abundant
applications in a wide range of systems. We propose a scheme to achieve the
controllable long-distance synchronization of two dissimilar optomechanical
systems, which are unidirectionally coupled through a fiber with light.
Synchronization, unsynchronization, and the dependence of the synchronization
on driving laser strength and intrinsic frequency mismatch are studied based on
the numerical simulation. Taking the fiber attenuation into account, it's shown
that two mechanical resonators can be synchronized over a distance of tens of
kilometers. In addition, we also analyze the unidirectional synchronization of
three optomechanical systems, demonstrating the scalability of our scheme.
