35 research outputs found
Stacked integrated double-disks for cavity optomechanics
The coupling of mechanical oscillators and optical cavity modes through scattering forces has received considerable attention in recent years [1]. This interaction provides a way, through the principle of dynamic back action [2], to amplify [2,3] and cool mechanical motion [4–6]. It could also soon provide a practical means to entangle macroscopic mechanical motion with a variety of other quantum systems, including light [7,8]. To date, experimental work has relied upon the optical scattering force to create conditions necessary for observation of dynamical back action effects. However, alongside the scattering force there are also dipole optical forces that can furnish optomechanical coupling. These forces, also referred to as dispersive or gradient forces, have been used to control coupling of a waveguide to a resonator [9] and to couple pairs of waveguides [10,11]. In the present work, a stacked, double-disk whispering gallery system is demonstrated as a new means to cavity optomechanical phenomena. Dipole-force coupling between the disks creates optomechnical coupling, causing displacement of the disks and tuning of the underlying whispering gallery resonances. In comparison to scattering-force-based systems, this double-disk configuration has the significant advantage of providing a larger optomechanical coupling constant, independent of the cavity round trip length
Coherent mixing of mechanical excitations in nano-optomechanical structures
The combination of the large per-photon optical force and small motional mass achievable in nanocavity optomechanical systems results in strong dynamical back-action between mechanical motion and the cavity light field. In this Article, we study the optical control of mechanical motion within two different nanocavity structures, a zipper nanobeam photonic crystal cavity and a double-microdisk whispering-gallery resonator. The strong optical gradient force within these cavities is shown to introduce significant optical rigidity into the structure, with the dressed mechanical states renormalized into optically bright and optically dark modes of motion. With the addition of internal mechanical coupling between mechanical modes, a form of optically controlled mechanical transparency is demonstrated in analogy to electromagnetically induced transparency of three-level atomic media. Based upon these measurements, a proposal for coherently transferring radio-frequency/microwave signals between the optical field and a long-lived dark mechanical state is described
Optical probing and actuation of microwave frequency phononic crystal resonators without clamping losses
We demonstrate microwave frequency mechanical modes of optomechanical crystals having arbitrarily
small clamping losses. The optomechanical crystals are connected to the substrate via a phononic bandgap
structure, simultaneously isolating and rigidly supporting the optomechanical resonator
Regular oscillations and random motion of glass microspheres levitated by a single optical beam in air
We experimentally report on optical binding of many glass particles in air that levitate in a single optical beam. A diversity of particle sizes and shapes interact at long range in a single Gaussian beam. Our system dynamics span from oscillatory to random and dimensionality ranges from 1 to 3D. The low loss for the center of mass motion of the beads could allow this system to serve as a standard many body testbed, similar to what is done today with atoms, but at the mesoscopic scale
Modeling Dispersive Coupling and Losses of Localized Optical and Mechanical Modes in Optomechanical Crystals
Periodically structured materials can sustain both optical and mechanical
excitations which are tailored by the geometry. Here we analyze the properties
of dispersively coupled planar photonic and phononic crystals: optomechanical
crystals. In particular, the properties of co-resonant optical and mechanical
cavities in quasi-1D (patterned nanobeam) and quasi-2D (patterned membrane)
geometries are studied. It is shown that the mechanical Q and optomechanical
coupling in these structures can vary by many orders of magnitude with modest
changes in geometry. An intuitive picture is developed based upon a
perturbation theory for shifting material boundaries that allows the
optomechanical properties to be designed and optimized. Several designs are
presented with mechanical frequency ~ 1-10 GHz, optical Q-factor Qo > 10^7,
motional masses meff 100 femtograms, optomechanical coupling length LOM < 5
microns, and a radiation-limited mechanical Q-factor Qm > 10^7.Comment: 25 pages, 9 figure
Synchronous micromechanically resonant programmable photonic circuits
Programmable photonic integrated circuits (PICs) are emerging as powerful
tools for the precise manipulation of light, with applications in quantum
information processing, optical range finding, and artificial intelligence. The
leading architecture for programmable PICs is the mesh of Mach-Zehnder
interferometers (MZIs) embedded with reconfigurable optical phase shifters.
Low-power implementations of these PICs involve micromechanical structures
driven capacitively or piezoelectrically but are limited in modulation
bandwidth by mechanical resonances and high operating voltages. However,
circuits designed to operate exclusively at these mechanical resonances would
reduce the necessary driving voltage from resonantly enhanced modulation as
well as maintaining high actuation speeds. Here we introduce a synchronous,
micromechanically resonant design architecture for programmable PICs, which
exploits micromechanical eigenmodes for modulation enhancement. This approach
combines high-frequency mechanical resonances and optically broadband phase
shifters to increase the modulation response on the order of the mechanical
quality factor , thereby reducing the PIC's power consumption,
voltage-loss product, and footprint. The architecture is useful for broadly
applicable circuits such as optical phased arrays, x , and x
photonic switches. We report a proof-of-principle programmable 1 x 8 switch
with piezoelectric phase shifters at specifically targeted mechanical
eigenfrequencies, showing a full switching cycle of all eight channels spaced
by approximately 11 ns and operating at >3x average modulation enhancement
across all on-chip modulators. By further leveraging micromechanical devices
with high , which can exceed 1 million, our design architecture should
enable a new class of low-voltage and high-speed programmable PICs.Comment: 18 pages, 5 figures, 5 supplementary figure
Characterization of radiation pressure and thermal effects in a nanoscale optomechanical cavity
Optical forces in guided-wave nanostructures have recently been proposed as
an effective means of mechanically actuating and tuning optical components. In
this work, we study the properties of a photonic crystal optomechanical cavity
consisting of a pair of patterned silicon nitride nanobeams. Internal stresses
in the stoichiometric silicon nitride thin-film are used to produce inter-beam
slot-gaps ranging from 560 to 40nm. A general pump-probe measurement scheme is
described which determines, self-consistently, the contributions of
thermo-mechanical, thermo-optic, and radiation pressure effects. For devices
with 40nm slot-gap, the optical gradient force is measured to be 134fN per
cavity photon for the strongly coupled symmetric cavity supermode, producing a
static cavity tuning greater than five times that of either the parasitic
thermo-mechanical or thermo-optic effects.Comment: 6 pages, 4 figure