  We propose a scheme via three-level cascade atoms to entangle two
optomechanical oscillators as well as two-mode fields. We show that two movable
mirrors and two-mode fields can be entangled even for bad cavity limit. We also
study entanglement of the output two-mode fields in frequency domain. The
results show that the frequency of the mirror oscillation and the injected
atomic coherence affect the output entanglement of the two-mode fields.
