Biomedical subjects

W Hoyer

Publications and source records attributed to W Hoyer.

5 recordsLinked to original sources

PubMed2006

Characterization of disorder in semiconductors via single-photon interferometry.

The method of angular photonic correlations of spontaneous emission is introduced as an experimental, purely optical scheme to characterize disorder in semiconductor nanostructures. The theoretical expression for the angular correlations is derived and numerically evaluated for a model system. The results demonstrate how the proposed experimental method yields direct information about the spatial distribution of the relevant states and thus on the disorder present in the system.

Journal Article↗

PubMed2005

Photoluminescence and terahertz emission from femtosecond laser-induced plasma channels.

Luminescence as a mechanism for terahertz emission from femtosecond laser-induced plasmas is studied. By using a fully microscopic theory, Coulomb scattering between electrons and ions is shown to lead to luminescence even for a spatially homogeneous plasma. The spectral features introduced by the rod geometry of laser-induced plasma channels in air are discussed on the basis of a generalized mode-function analysis.

Journal Article↗

PubMed2004

Entanglement between a photon and a quantum well.

The lack of translational invariance perpendicular to the plane of a single quantum well causes equal probability for spontaneous emission to the left or right. Combining one emission path from the left and one from the right into a common detector leads to interference fringes for fundamentally indistinguishable paths corresponding to geometries where the same in-plane momentum is transferred to the quantum well. For all other paths, no interference is observed because of the entanglement between the photon and extended Bloch states of the many-body system. In multiple-quantum-well structures the interference can be controlled via the spacing between the wells.

Journal Article↗

PubMed2004

Excitonic photoluminescence in semiconductor quantum wells: plasma versus excitons.

Time-resolved photoluminescence spectra after nonresonant excitation show a distinct 1s resonance, independent of the existence of bound excitons. A microscopic analysis identifies exciton and electron-hole plasma contributions. For low temperatures and low densities, the excitonic emission is extremely sensitive to details of the electron-hole-pair population making it possible to identify even minute fractions of optically active excitons.

Journal Article↗

PubMed2001

Exciton formation in semiconductors and the influence of a photonic environment.

A fully microscopic theory is presented for interacting electrons, holes, photons, and phonons in semiconductor heterostructures. The formation dynamics and statistics of incoherent excitons are analyzed for different densities, lattice temperatures, and photonic environments. Luminescence experiments are shown to depend strongly on the photonic environment in contrast to suggested terahertz absorption measurements. Whereas luminescence in free space is dominated by plasma contributions, terahertz absorption should be able to directly measure excitonic populations.

Journal Article↗