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THz radiation field emitted by a [100] oriented CdTe wafer is studied. Quantum interference between single- and two-photon absorption pathways of fundamental (omega) and second-harmonic (2omega) 150 fs optical pulses enables the optical injection of ballistic electron and hole currents in bulk semiconductors.
Ballistic charge currents are injected into Ge and Si and pure spin currents into Ge using quantum interference techniques and are spatially and temporally resolved for the first time.
The interference between the two exciton polaritons in semiconductors is predicted to give a time delay for traversing light pulses that is unrelated to the polaritons' group velocities.
We demonstrate the spatial separation of right and left circularly polarized components of a linear polarized beam non-normally incident at an air-GaAs interface through the transverse separation of optically injected up- and down-spin electrons.
Using a microscopic theory, we predict all-optical switching in planar semiconductor micro-cavities where a weak beam switches a stronger signal. The scheme is similar to that recently demonstrated in atomic vapors.
Ballistic pure charge currents are injected into GaAs quantum wells using quantum interference techniques and are spatially and temporally resolved for the first time. The dynamics are dominated by momentum relaxation and space charge effects.
Spin- and polarization-dependent ultrafast blue shifts, transient gain and self-wave-mixing are observed in Bragg-spaced InGaAs/GaAs quantum wells. The data are in agreement with a microscopic theory.
The control of spin for technological purposes, known as spintronics, is usually discussed in terms of how one can use specially prepared materials (e.g., ferromagnetic semiconductors) or nanogeometries to manipulate spin, via electrical potentials. In recent years we, together with students and postdoctoral fellows, have explored how optics may contribute to spin manipulation and control. Since a...
An integrated AlGaAs all-optical 188-ps delay line is characterized over the C- and L- bands. Self-switching by input intensity is achieved using a nonlinear directional coupler and a racetrack delay line.
Using microring resonator structures it should be possible to greatly enhance second order optical effects in AlGaAs, even in the presence of material and modal dispersion, without any artificially constructed variation in chi(2) in the resonator. We consider a number of second-order processes, and examine the limitations due to realistic scattering losses
We present a microscopic theory for the nonlinear reflection of semiconductor Bragg structures. Our theoretical results showing ultrafast optical gain complement recent experimental observations and allow for the identification of the underlying many-particle processes.
Ballistic pure spin currents generated via quantum interference in the absorption of femtosecond pulses are demonstrated to produce transverse ballistic Hall pure charge currents and vice versa via spin-dependent asymmetric scattering processes.
When energy of the probe pulse is well above the band gap, we demonstrate that the correct spin relaxation time in bulk GaAs can be inferred only after carrier cooling, band dispersion and carrier statistics are taken into account
We review our theoretical and experimental studies of the optical injection in semiconductors of spin-polarized currents, and pure spin currents, by oneand two-photon absorption across the band gap
We demonstrate a formal similarity between the evolution equation of the third-order interband polarization in a phenomenological model and that in microscopic theories for semiconductor optics, thereby providing a microscopic interpretation of the phenomenological model
We use pump-probe experiments to demonstrate that the spin polarization of electrons photogenerated in bulk GaAs by two-photon absorption of circularly polarized light is not significantly larger than by one-photon absorption, in agreement with theory
We demonstrate independent coherent control of carrier density and spin in [110]-oriented GaAs/AlGaAs quantum wells by using the phase-dependent energy transfer between ~100-fs omega and 2omega pulses, as opposed to quantum interference
Transient grating techniques are used to contrast and compare spin-polarized current, unpolarized charge current, and pure spin current (i.e., no charge current) gratings that are injected by quantum interference
Summary form only given. We use spectral interferometry and temporal gating techniques to investigate the time-integrated quantum beats (TI-QBs) involving the light hole (lh) and heavy hole (hh) excitons in GaAs-AlGaAs quantum wells in a geometry that is sensitive both to the nonradiative Raman coherence and to the radiative dipole coherence associated with the dynamic interactions between hh and...
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