  In contrast to the optomechanically induced transparency (OMIT) defined
conventionally, the inverse OMIT behaves as coherent absorption of the input
lights in the optomechanical systems. We characterize a feasible inverse OMIT
in a multi-channel fashion with a double-sided optomechanical cavity system
coupled to a nearby charged nanomechanical resonator via Coulomb interaction,
where two counter-propagating probe lights can be absorbed via one of the
channels or even via three channels simultaneously with the assistance of a
strong pump light. Under realistic conditions, we demonstrate the experimental
feasibility of our model using two slightly different nanomechanical resonators
and the possibility of detecting the energy dissipation of the system. In
particular, we find that our model turns to be an unilateral inverse OMIT once
the two probe lights are different with a relative phase, and in this case we
show the possibility to measure the relative phase precisely.
