33 research outputs found
Mechanically Compliant Grating Reflectors for Optomechanics
We demonstrate micromechanical reflectors with a reflectivity as large as
99.4% and a mechanical quality factor Q as large as 7.8*10^5 for optomechanical
applications. The reflectors are silicon nitride membranes patterned with
sub-wavelength grating structures, obviating the need for the many dielectric
layers used in conventional mirrors. We have employed the reflectors in the
construction of a Fabry-Perot cavity with a finesse as high as F=1200, and used
the optical response to probe the mechanical properties of the membrane. By
driving the cavity with light detuned to the high-frequency side of a cavity
resonance, we create an optical antidamping force that causes the reflector to
self-oscillate at 211 kHz
Emission spectrum of a dressed exciton-biexciton complex in a semiconductor quantum dot
The photoluminescence spectrum of a single quantum dot was recorded as a
secondary resonant laser optically dressed either the vacuum-to-exciton or the
exciton-to-biexciton transitions. High-resolution polarization-resolved
measurements using a scanning Fabry-Perot interferometer reveal splittings of
the linearly-polarized fine-structure states that are non-degenerate in an
asymmetric quantum dot. These splittings manifest as either triplets or
doublets and depend sensitively on laser intensity and detuning. Our approach
realizes complete resonant control of a multi-excitonic system in emission,
which can be either pulsed or continuous-wave, and offers direct access to the
emitted photons.Comment: 4 pages, 4 figure
Active feedback of a Fabry-Perot cavity to the emission of a single InAs/GaAs quantum dot
We present a detailed study of the use of Fabry-Perot (FP) cavities for the
spectroscopy of single InAs quantum dots (QDs). We derive optimal cavity
characteristics and resolution limits, and measure photoluminescence linewidths
as low as 0.9 GHz. By embedding the QDs in a planar cavity, we obtain a
sufficiently large signal to actively feed back on the length of the FP to lock
to the emission of a single QD with a stability below 2% of the QD linewidth.
An integration time of approximately two seconds is found to yield an optimum
compromise between shot noise and cavity length fluctuations.Comment: 7 pages, 3 figure
Transforaminal Blood Patch for the Treatment of Chronic Headache from Intracranial Hypotension: A Case Report and Review
This case report describes the successful treatment of chronic headache from intracranial hypotension with bilateral transforaminal (TF) lumbar epidural blood patches (EBPs). The patient is a 65-year-old male with chronic postural headaches. He had not had a headache-free day in more than 13 years. Conservative treatment and several interlaminar epidural blood patches were previously unsuccessful. A transforaminal EBP was performed under fluoroscopic guidance. Resolution of the headache occurred within 5 minutes of the procedure. After three months without a headache the patient had a return of the postural headache. A second transforaminal EBP was performed again with almost immediate resolution. The patient remains headache-free almost six months from the time of first TF blood patch. This is the first published report of the use of transforaminal epidural blood patches for the successful treatment of a headache lasting longer than 3 months