59 research outputs found
Spin noise spectroscopy of a single-quantum-well microcavity
We report on the first experimental observation of spin noise in a single
semiconductor quantum well embedded into a microcavity. The great
cavity-enhanced sensitivity to fluctuations of optical anisotropy has allowed
us to measure the Kerr rotation and ellipticity noise spectra in the strong
coupling regime. The spin noise spectra clearly show two resonant features: a
conventional magneto-resonant component shifting towards higher frequencies
with magnetic field and an unusual "nonmagnetic" component centered at zero
frequency and getting suppressed with increasing magnetic field. We attribute
the first of them to the Larmor precession of free electron spins, while the
second one being presumably due to hyperfine electron-nuclei spin interactions.Comment: 5 pages, 6 figures + supplement (4 pages, 1 figure
Optics of spin-noise-induced gyrotropy of asymmetric microcavity
The optical gyrotropy noise of a high-finesse semiconductor Bragg microcavity
with an embedded quantum well (QW) is studied at different detunings of the
photon mode and the QW exciton resonances. A strong suppression of the noise
magnitude for the photon mode frequencies lying above exciton resonances is
found. We show that such a critical behavior of the observed optical noise
power is specific of asymmetric Fabry-Perot resonators. As follows from our
analysis, at a certain level of intracavity loss, the reflectivity of the
asymmetric resonator vanishes, while the polarimetric sensitivity to the
gyrotropy changes dramatically when moving across the critical point. The
results of model calculations are in a good agreement with our experimental
data on the spin noise in a single-quantum-well microcavity and are confirmed
also by the spectra of the photo-induced Kerr rotation in the pump-probe
experiments.Comment: 6 pages, 5 figure
Optically Controlled Excitonic Transistor
Optical control of exciton fluxes is realized for indirect excitons in a
crossed-ramp excitonic device. The device demonstrates experimental proof of
principle for all-optical excitonic transistors with a high ratio between the
excitonic signal at the optical drain and the excitonic signal due to the
optical gate. The device also demonstrates experimental proof of principle for
all-optical excitonic routers
Magnetic field control of photon echo in the electron-trion system: Shuffling of coherences between optically accessible and inaccessible states
We report on magnetic field induced oscillations of the photon echo signal
from negatively charged excitons in a CdTe/(Cd,Mg)Te semiconductor quantum
well. The oscillatory signal is due to Larmor precession of the electron spin
about a transverse magnetic field and depends sensitively on the polarization
configuration of the exciting and refocusing pulses. The echo amplitude can be
fully tuned from maximum down to zero depending on the time delay between the
two pulses and the magnetic field strength. The results are explained in terms
of the optical Bloch equations accounting for the spin level structure of
electron and trion.Comment: 8 pages, 2 figure
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