Dispersion and damping of multi-quantum well polaritons from resonant Brillouin scattering by folded acoustic modes

We report on confined exciton resonances of acoustic and folded acoustic phonon light scattering in a GaAs/AlAs multi-quantum-well. Significant variations of the line shifts and widths are observed across the resonance and quantitatively reproduced in terms of the polariton dispersion. This high resolution Brillouin study brings new unexpectedly detailed informations on the polariton dynamics in confined systems

Uncoupled excitons in semiconductor microcavities detected in resonant Raman scattering

We present an outgoing resonant Raman-scattering study of a GaAs/AlGaAs based microcavity embedded in a p-i-n junction. The p-i-n junction allows the vertical electric field to be varied, permitting control of exciton-photon detuning and quenching of photoluminescence which otherwise obscures the inelastic light scattering signals. Peaks corresponding to the upper and lower polariton branches are observed in the resonant Raman cross sections, along with a third peak at the energy of uncoupled excitons. This third peak, attributed to disorder activated Raman scattering, provides clear evidence for the existence of uncoupled exciton reservoir states in microcavities in the strong-coupling regime

Phonon Bloch oscillations in acoustic-cavity structures

We describe a semiconductor multilayer structure based in acoustic phonon cavities and achievable with MBE technology, designed to display acoustic phonon Bloch oscillations. We show that forward and backscattering Raman spectra give a direct measure of the created phononic Wannier-Stark ladder. We also discuss the use of femtosecond laser impulsions for the generation and direct probe of the induced phonon Bloch oscillations. We propose a gedanken experiment based in an integrated phonon source-structure-detector device, and we present calculations of pump and probe time dependent optical reflectivity that evidence temporal beatings in agreement with the Wannier-Stark ladder energy splitting.Comment: PDF file including 4 figure

Cavity Optomechanics with a Laser Engineered Optical Trap

Laser engineered exciton-polariton networks could lead to dynamically configurable integrated optical circuitry and quantum devices. Combining cavity optomechanics with electrodynamics in laser configurable hybrid designs constitutes a platform for the vibrational control, conversion, and transport of signals. With this aim we investigate 3D optical traps laser-induced in quantum-well embedded semiconductor planar microcavities. We show that the laser generated and controlled discrete states of the traps dramatically modify the interaction between photons and phonons confined in the resonators, accessing through coupling of photoelastic origin $g_\mathrm{0}/2\pi\sim 1.7$ MHz an optomechanical cooperativity $C>1$ for mW excitation. The quenching of Stokes processes and double-resonant enhancement of anti-Stokes ones involving pairs of discrete optical states in the side-band resolved regime, allows the optomechanical cooling of 180 GHz bulk acoustic waves, starting from room temperature down to $\sim120$ K. These results pave the way for dynamical tailoring of optomechanical actuation in the extremely-high-frequency range (30-300 GHz) for future network and quantum technologies.Comment: 22 pages, 14 figure

Microcavity phonoritons -- a coherent optical-to-microwave interface

Optomechanical systems provide a pathway for the bidirectional optical-to-microwave interconversion in (quantum) networks. We demonstrate the implementation of this functionality and non-adiabatic optomechanical control in a single, $\mu$m-sized potential trap for phonons and exciton-polariton condensates in a structured semiconductor microcavity. The exciton-enhanced optomechanical coupling leads to self-oscillations (phonon lasing) -- thus proving reversible photon-to-phonon conversion. We show that these oscillations are a signature of the optomechanical strong coupling signalizing the emergence of elusive phonon-exciton-photon quasiparticles -- the phonoritons. We then demonstrate full control of the phonoriton spectrum as well as coherent microwave-to-photon interconversion using electrically generated GHz-vibrations and a resonant optical laser beam. These findings establish the zero-dimensional polariton condensates as a scalable coherent interface between microwave and optical domains with enhanced microwave-to-mechanical and mechanical-to-optical coupling rates

Post-Prior discrepancies in CDW-EIS calculations for ion impact ionization fully differential cross sections

In this work we present fully differential cross sections (FDCSs) calculations using post and prior version of CDW--EIS theory for helium single ionization by 100 MeV C$^{6+}$ amu$^{-1}$ and 3.6 MeV amu$^{-1}$ Au$^{24+}$ and Au$^{53+}$ ions. We performed our calculations for different momentum transfer and ejected electron energies. The influence of internuclear potential on the ejected electron spectra is taken into account in all cases. We compare our calculations with absolute experimental measurements. It is shown that prior version calculations give better agreement with experiments in almost all studied cases.Comment: 9 pages, 7 figure

Optical cavity mode dynamics and coherent phonon generation in high-Q micropillar resonators

International audienceWe study the temporal dynamics of photoexcited carriers in distributed Bragg reflector based semiconductor micropillars at room temperature. Their influence on the process of coherent phonon generation and detection is analyzed by means of pump-probe microscopy. The dependence of the measured mechanical signatures on laser-cavity detuning is explained through a model that accounts for the varying light-cavity coupling existent during the ultrashort times that pump and probe pulses dwell within the structure. To do so, we first explain the optical mode dynamics with an electron-hole diffusion model that accounts for the escape of carriers from the probed area, as well as their recombination in the bulk and on the free surfaces. We thus show that the latter is the most influential factor for pillars below ∼10μm, where 3D confinement of the optical and mechanical fields becomes relevant