259 research outputs found
Exciton-photon coupling in a ZnSe based microcavity fabricated using epitaxial liftoff
We report the observation of strong exciton-photon coupling in a ZnSe based
microcavity fabricated using epitaxial liftoff. Molecular beam epitaxial grown
ZnSe/ZnCdSe quantum wells with a one wavelength optical length
at the exciton emission were transferred to a SiO/TaO mirror with a
reflectance of 96% to form finesse matched microcavities. Analysis of our angle
resolved transmission spectra reveals key features of the strong coupling
regime: anticrossing with a normal mode splitting of at ;
composite evolution of the lower and upper polaritons; and narrowing of the
lower polariton linewidth near resonance. The heavy hole exciton oscillator
strength per quantum well is also deduced to be .Comment: 3 pages, 3 figure
Ultimate photo-induced Kerr rotation achieved in semiconductor microcavities
Photoinduced Kerr rotation by more than radians is demonstrated in
planar quantum well microcavity in the strong coupling regime. This result is
close to the predicted theoretical maximum of . It is achieved by
engineering microcavity parameters such that the optical impedance matching
condition is reached at the smallest negative detuning between exciton
resonance and the cavity mode. This ensures the optimum combination of the
exciton induced optical non-linearity and the enhancement of the Kerr angle by
the cavity. Comprehensive analysis of the polarization state of the light in
this regime shows that both renormalization of the exciton energy and the
saturation of the excitonic resonance contribute to the observed optical
nonlinearities.Comment: Shortened version prepared to submit in Phys. Rev. Letter
Nuclear spin warm-up in bulk n-GaAs
We show that the spin-lattice relaxation in n-type insulating GaAs is
dramatically accelerated at low magnetic fields. The origin of this effect,
that cannot be explained in terms of well-known diffusion-limited hyperfine
relaxation, is found in the quadrupole relaxation, induced by fluctuating donor
charges. Therefore, quadrupole relaxation, that governs low field nuclear spin
relaxation in semiconductor quantum dots, but was so far supposed to be
harmless to bulk nuclei spins in the absence of optical pumping can be studied
and harnessed in much simpler model environment of n-GaAs bulk crystal.Comment: 5 pages, 4 figure
Spin-to-Orbital Angular Momentum Conversion in Semiconductor Microcavities
We experimentally demonstrate a technique for the generation of optical beams
carrying orbital angular momentum using a planar semiconductor microcavity.
Despite being isotropic systems, the transverse electric - transverse magnetic
(TE-TM) polarization splitting featured by semiconductor microcavities allows
for the conversion of the circular polarization of an incoming laser beam into
the orbital angular momentum of the transmitted light field. The process
implies the formation of topological entities, a pair of optical half-vortices,
in the intracavity field
- …