2 research outputs found
Laser interferometry with translucent and absorbing mechanical oscillators
The sensitivity of laser interferometers can be pushed into regimes that
enable the direct observation of quantum behaviour of mechanical oscillators.
In the past, membranes with subwavelength thickness (thin films) have been
proposed as high-mechanical-quality, low-thermal-noise oscillators. Thin films
from a homogenous material, however, generally show considerable light
transmission accompanied by heating due to light absorption, which typically
reduces the mechanical quality and limits quantum opto-mechanical experiments
in particular at low temperatures. In this work, we experimentally analyze a
Michelson-Sagnac interferometer including a translucent silicon nitride (SiN)
membrane with subwavelength thickness. We find that such an interferometer
provides an operational point being optimally suited for quantum
opto-mechanical experiments with translucent oscillators. In case of a balanced
beam splitter of the interferometer, the membrane can be placed at a node of
the electro-magnetic field, which simultaneously provides lowest absorption and
optimum laser noise rejection at the signal port. We compare the optical and
mechanical model of our interferometer with experimental data and confirm that
the SiN membrane can be coupled to a laser power of the order of one Watt at
1064 nm without significantly degrading the membrane's quality factor of the
order 10^6, at room temperature
Optomechanical sideband cooling of a thin membrane within a cavity
We present an experimental study of dynamical back-action cooling of the
fundamental vibrational mode of a thin semitransparent membrane placed within a
high-finesse optical cavity. We study how the radiation pressure interaction
modifies the mechanical response of the vibrational mode, and the experimental
results are in agreement with a Langevin equation description of the coupled
dynamics. The experiments are carried out in the resolved sideband regime, and
we have observed cooling by a factor 350 We have also observed the mechanical
frequency shift associated with the quadratic term in the expansion of the
cavity mode frequency versus the effective membrane position, which is
typically negligible in other cavity optomechanical devices.Comment: 15 pages, 7 figure