18 research outputs found
Optical design of split-beam photonic crystal nanocavities
We design high quality factor photonic crystal nanobeam cavities formed by
two mechanically isolated cantilevers. These "split-beam" cavities have a
physical gap at the center, allowing mechanical excitations of one or both of
the cavity halves. They are designed by analyzing the optical band structures
and mode profiles of waveguides perforated by elliptical holes and rectangular
gaps, and are predicted to support optical resonances with quality factors
exceeding 1E6 at wavelengths of ~ 1.6 um.Comment: To appear in Optics Letter
Cavity optomechanics in gallium phosphide microdisks
We demonstrate gallium phosphide (GaP) microdisk optical cavities with
intrinsic quality factors and mode volumes , and study their nonlinear and optomechanical properties. For
optical intensities up to intracavity photons, we observe
optical loss in the microcavity to decrease with increasing intensity,
indicating that saturable absorption sites are present in the GaP material, and
that two-photon absorption is not significant. We observe optomechanical
coupling between optical modes of the microdisk around 1.5 m and several
mechanical resonances, and measure an optical spring effect consistent with a
theoretically predicted optomechanical coupling rate kHz for
the fundamental mechanical radial breathing mode at 488 MHz.Comment: Published Versio
Single crystal diamond nanobeam waveguide optomechanics
Optomechanical devices sensitively transduce and actuate motion of
nanomechanical structures using light. Single--crystal diamond promises to
improve the performance of optomechanical devices, while also providing
opportunities to interface nanomechanics with diamond color center spins and
related quantum technologies. Here we demonstrate dissipative
waveguide--optomechanical coupling exceeding 35 GHz/nm to diamond nanobeams
supporting both optical waveguide modes and mechanical resonances, and use this
optomechanical coupling to measure nanobeam displacement with a sensitivity of
fm/ and optical bandwidth nm. The nanobeams are
fabricated from bulk optical grade single--crystal diamond using a scalable
undercut etching process, and support mechanical resonances with quality factor
at room temperature, and in cryogenic
conditions (5K). Mechanical self--oscillations, resulting from interplay
between photothermal and optomechanical effects, are observed with amplitude
exceeding 200 nm for sub-W absorbed optical power, demonstrating the
potential for optomechanical excitation and manipulation of diamond
nanomechanical structures.Comment: Minor changes. Corrected error in units of applied stress in Fig. 1
Design and experimental demonstration of optomechanical paddle nanocavities
We present the design, fabrication and initial characterization of a paddle
nanocavity consisting of a suspended sub-picogram nanomechanical resonator
optomechanically coupled to a photonic crystal nanocavity. The optical and
mechanical properties of the paddle nanocavity can be systematically designed
and optimized, and key characteristics including mechanical frequency easily
tailored. Measurements under ambient conditions of a silicon paddle nanocavity
demonstrate an optical mode with quality factor ~ 6000 near 1550 nm, and
optomechanical coupling to several mechanical resonances with frequencies
~ 12-64 MHz, effective masses ~ 350-650 fg, and
mechanical quality factors ~ 44-327. Paddle nanocavities are promising
for optomechanical sensing and nonlinear optomechanics experiments.Comment: 5 pages, 4 figure
Dissipative and Dispersive Optomechanics in a Nanocavity Torque Sensor
Dissipative and dispersive optomechanical couplings are experimentally
observed in a photonic crystal split-beam nanocavity optimized for detecting
nanoscale sources of torque. Dissipative coupling of up to approximately
MHz/nm and dispersive coupling of GHz/nm enable measurements of sub-pg
torsional and cantilever-like mechanical resonances with a thermally-limited
torque detection sensitivity of 1.2 in ambient conditions and 1.3 in low vacuum. Interference between
optomechanical coupling mechanisms is observed to enhance detection sensitivity
and generate a mechanical-mode-dependent optomechanical wavelength response.Comment: 11 pages, 6 figure
Solving dielectric and plasmonic waveguide dispersion relations with a pocket calculator
We present a robust iterative technique for solving complex transcendental
dispersion equations routinely encountered in integrated optics. Our method
especially befits the multilayer dielectric and plasmonic waveguides forming
the basis structures for a host of contemporary nanophotonic devices. The
solution algorithm ports seamlessly from the real to the complex domain--i.e.,
no extra complexity results when dealing with leaky structures or those with
material/metal loss. Unlike several existing numerical approaches, our
algorithm exhibits markedly-reduced sensitivity to the initial guess and allows
for straightforward implementation on a pocket calculator.Comment: 18 pages, 11 Figures, 5 Tables, added references, Submitted to Optics
Expres
Near-field cavity optomechanical probing of nanomechanics
An optical fiber taper placed in the near field of a "split-beam" photonic crystal nanobeam cavity with a physical gap at the cavity center breaks the system's vertical dielectric symmetry, enabling selective optomechanical coupling to multiple cantilever resonances using a single optical nanocavity mode. \ua9 2013 Optical Society of America.Peer reviewed: YesNRC publication: Ye