ABSTRACT
The field of optomechanics has emerged as a new interface for light-
matter interactions, paving the way to the implementation of micro-
or even nano-optomechanical systems (MOMS/NOMS) in integrated
circuits [1]. Functionalities such as ultrasensitive detection of small
displacements or weights and possible uses in quantum information
processing are some of the appealing applications driving the fast
developments in this area. One of the most appealing features in
the optomechanics field is the possibility of momentum exchange
between photons confined within an optical cavity and mechanical
devices that are either inside or part of the cavity. Photons in
an optomechanical (OM) cavity can be converted into phonons in
the mechanical device and vice versa. Thus, if a pumping laser
wavelength is tuned to a slightly lower frequency than the resonance
of the optical cavity, the light can be used to perform optically
induced damping of the mechanical motion, thus effectively cooling
the oscillator. Research toward this goal has rapidly progressed
and culminated in the use of optical forces to cool nanoscale
mechanical oscillators into their quantum ground state of motion
at temperatures of about 20 K [2]. On the other hand, if the
pumping laser is tuned to the other side of the optical resonance,
the OM cavity could be driven into the opposite regime [3, 4].
In microscale structures a high-amplitude regime can be achieved
and optically driven phonon lasing on the MHz range has been
recently reported [5], though efficiencies are rather low because
of the strong damping due to the interaction with the surrounding
medium and the low photon-phonon coupling. Great advances along
this direction have been reached and recently the first nonvolatile
nanomechanical memory cell that is operated exclusively by light
has been reported, exploiting both the effects of blue-detuning
the pump laser and the existence of two stable mechanical states
[6]. The nanoscale OM crystal (with both phononic and photonic
bandgaps) regime promises stronger phonon-photon couplings,
resonant mechanical frequencies scaled up to the gigahertz, and
lower damping processes.
