220 research outputs found
Optomechanical coupling in photonic crystal supported nanomechanical waveguides
We report enhanced optomechanical coupling by embedding a nano-mechanical
beam resonator within an optical race-track resonator. Precise control of the
mechanical resonator is achieved by clamping the beam between two low-loss
photonic crystal waveguide couplers. The low insertion loss and the rigid
mechanical support provided by the couplers yield both high mechanical and
optical Q-factors for improved signal quality
Second harmonic generation in phase matched aluminum nitride waveguides
We demonstrate second order optical nonlinearity in aluminum nitride on
insulator substrates. Using sputter-deposited aluminum nitride thin films we
realize nanophotonic waveguides coupled to micro-ring resonators that
simultaneously support cavity resonant modes for both visible and IR light. By
using phase matched ring resonators, we achieve efficient second-harmonic
generation and are able to generate up to 0.5uW of visible light on the chip
with a conversion efficiency of -46dB. From the measured response we obtain a
second order non-linear susceptibility (\c{hi}2) of 4.7pm/V. Our platform
provides a viable route for realizing wideband linear and nonlinear optical
devices on a chip
Diamond electro-optomechanical resonators integrated in nanophotonic circuits
Diamond integrated photonic devices are promising candidates for emerging
applications in nanophotonics and quantum optics. Here we demonstrate active
modulation of diamond nanophotonic circuits by exploiting mechanical degrees of
freedom in free-standing diamond electro-optomechanical resonators. We obtain
high quality factors up to 9600, allowing us to read out the driven
nanomechanical response with integrated optical interferometers with high
sensitivity. We are able to excite higher order mechanical modes up to 115 MHz
and observe the nanomechanical response also under ambient conditions.Comment: 15 pages, 4 figure
Decoherence and the Nature of System-Environment Correlations
We investigate system-environment correlations based on the exact dynamics of
a qubit and its environment in the framework of pure decoherence (phase
damping). We focus on the relation of decoherence and the build-up of
system-reservoir entanglement for an arbitrary (possibly mixed) initial qubit
state. In the commonly employed regime where the qubit dynamics can be
described by a Markov master equation of Lindblad type, we find that for almost
all qubit initial states inside the Bloch sphere, decoherence is complete while
the total state is still separable - no entanglement is involved. In general,
both "separable" and "entangling" decoherence occurs, depending on temperature
and initial qubit state. Moreover, we find situations where classical and
quantum correlations periodically alternate as a function of time in the regime
of low temperatures
High-Q aluminum nitride photonic crystal nanobeam cavities
We demonstrate high optical quality factors in aluminum nitride (AlN)
photonic crystal nanobeam cavities. Suspended AlN photonic crystal nanobeams
are fabricated in sputter-deposited AlN-on-insulator substrates using a
self-protecting release process. Employing one-dimensional photonic crystal
cavities coupled to integrated optical circuits we measure quality factors up
to 146,000. By varying the waveguide-cavity coupling gap, extinction ratios in
excess of 15 dB are obtained. Our results open the door for integrated photonic
bandgap structures made from a low loss, wide-transparency, nonlinear optical
material system
High-Q optomechanical circuits made from polished nanocrystalline diamond thin films
We demonstrate integrated optomechanical circuits with high mechanical
quality factors prepared from nanocrystalline diamond thin films. Using
chemomechanical polishing, the RMS surface roughness of as grown
polycrystalline diamond films is reduced below 3nm to allow for the fabrication
of high-quality nanophotonic circuits. By integrating free-standing
nanomechanical resonators into integrated optical devices, efficient read-out
of the thermomechanical motion of diamond resonators is achieved with on-chip
Mach-Zehnder interferometers. Mechanical quality factors up to 28,800 are
measured for four-fold clamped optomechanical resonators coupled to the
evanescent near-field of nanophotonic waveguides. Our platform holds promise
for large-scale integration of optomechanical circuits for on-chip metrology
and sensing applications
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