  A pulsed scheme for generating robust optical entanglement via the coupling
of two optical modes to a mechanical oscillator is proposed. This scheme is
inspired by the S{\o}rensen-M{\o}lmer approach for entangling trapped ions in a
thermal environment and is based on the use of optical driving pulses that are
slightly detuned from the respective sideband resonance. We show that for
certain pulse durations, the optomechanical interaction can return the
mechanical oscillator to its initial state. The corresponding entanglement
generation is robust against thermal mechanical noise in the weak as well as
the strong coupling regimes. Significant optical entanglement can be generated
in the weak coupling regime, even in the presence of a large thermal phonon
occupation.
