Search results for "Toe"

Photoelectric effect from a metal surface: a revisited theoretical model

1992

The Sommerfeld model extended to include radiation–electron interaction in the regime of highly intense fields is taken as the basis for studying theoretically the laser multiphoton photoelectric effect from a metal surface. Numerical analysis is carried out without approximations other than those inherent in the model itself; the study of the multiphoton aspect of the problem is based on a scheme that is nonperturbative in an essential way. The numerical analysis facilitates insight into the potential and the limits of the model in the interpretation of recent experiments and into the similarities and differences between the metal multiphoton effect and atomic multiphoton ionization. The r…

Effect of quantum efficiency on the performance of multijunction tandem cells

2015

New insight into the potential of practical solar cells can be given through alternative modeling approaches like Monte Carlo simulations. In the present work, the performance of three stacks of cells connected in series was examined at different levels of internal quantum efficiency. Incident photons, generated by employing the ASTM G173-03 and E490-00a data sets, are accounted for individually as they interact with the stack of cells. The values of the different bandgaps were chosen from a paper by K. Tanabe (2009), and the performance was studied based on photon dynamics.

2014

N-type CdO is a transparent conducting oxide (TCO) which has promise in a number of areas including solar cell applications. In order to realize this potential a detailed knowledge of the electronic structure of the material is essential. In particular, standard density functional theory (DFT) methods struggle to accurately predict fundamental material properties such as the band gap. This is largely due to the underestimation of the Cd 4d binding energy, which results in a strong hybridization with the valence-band (VB) states. In order to test theoretical approaches, comparisons to experiment need to be made. Here, synchrotron-radiation photoelectron spectroscopy (SR-PES) measurements are…

On-chip Generation, Coherent Control and Processing of Complex Entangled Photon States

2019

We demonstrate the on-chip generation of time-bin entangled two- and multi-photon qubit states, as well as high-dimensional frequency-entangled photon pairs. Combining time and frequency entanglement, we generate high-dimensional optical cluster states and implement proof-of-concept high-dimensional one-way quantum computing. This, by using standard, fiber-based telecommunication components.

Timing Control of a Heralded Single Photon Emission

2012

We experimentally demonstrate controlling the emission timing of a heralded single photon from a non-degenerate optical parametric oscillator, by placing another quickly tunable cavity at the exit as a shutter.

MuPix7 - A fast monolithic HV-CMOS pixel chip for Mu3e

2016

The MuPix7 chip is a monolithic HV-CMOS pixel chip, thinned down to 50 \mu m. It provides continuous self-triggered, non-shuttered readout at rates up to 30 Mhits/chip of 3x3 mm^2 active area and a pixel size of 103x80 \mu m^2. The hit efficiency depends on the chosen working point. Settings with a power consumption of 300 mW/cm^2 allow for a hit efficiency >99.5%. A time resolution of 14.2 ns (Gaussian sigma) is achieved. Latest results from 2016 test beam campaigns are shown.

Excitation power dependence of the Purcell effect in photonic crystal microcavity lasers with quantum wires

2013

The Purcell effect dependence on the excitation power is studied in photonic crystal microcavity lasers embedding InAs/InP quantum wires. In the case of non-lasing modes, the Purcell effect has low dependence on the optical pumping, attributable to an exciton dynamics combining free and localized excitons. In the case of lasing modes, the influence of the stimulated emission makes ambiguous the determination of the Purcell factor. We have found that this ambiguity can be avoided by measuring the dependence of the decay time on the excitation power. These results provide insights in the determination of the Purcell factor in microcavity lasers. © 2013 AIP Publishing LLC.

Acousto-optical multiple interference switches

2007

The authors introduce an alternative approach for acousto-optical light control based on the interference of light propagating through several waveguides, each subjected to a periodic refractive index modulation induced by a surface acoustic wave. The feasibility of the concept is demonstrated by the realization of an optical switch for arbitrary time intervals with an on/off contrast ratio of 20.

Coherence functions of the electrical and the optical noises in monomodal packaged vertical cavity surface emitting lasers

2006

Calculations of the frequency noise spectra and of the coherence functions between the electrical and the optical noises for a single-mode packaged vertical surface emitting laser (VCSEL) are reported.A rate-equation model for an index guided VCSEL is used, implemented with the electrical noise model including the intrinsic device, the package and external bias network.The extended model works up to the laser relaxation frequency. The amplitude optical noise and its correlation with the frequency and electrical noises are also analysed. The influence on the calculated quantities of some electrical and laser parameters is evaluated. The results show that generally the frequency noise is corr…

Semitoroidal detector configuration for large (well-type) Ge(Li) detectors

1972

Abstract A “semitoroidal” detector configuration intended for making large Ge(Li) detectors with approximately homogeneous electric fields is described in detail. Test measurements have been carried out with a relatively small semitoroidal detector. The performance of the semitoroidal detector having a volume of more than 150 cm 3 is discussed.