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124 results on '"Leosson, K."'

9. Net optical gain in a plasmonic waveguide embedded in a fluorescent polymer

Author

Gather, M., Meerholz, K., Danz, N., Leosson, K., and Publica

Subjects
conjugated polymer, thin film, stimulated emission, surface plasmon, media, performance
Abstract

Plasmonics - the study of the interaction between electromagnetic waves and electron plasmas on metal surfaces and in metallic nanostructures - has received much attention in recent years, with potential new applications ranging from subwavelength photonic circuits to photothermal cancer therapy. In many cases, however, the substantial attenuation of the electromagnetic wave due to absorption (ohmic loss) in the metal is of serious concern. Introduction of optical gain into the dielectric material adjacent to the metal surface has been identified as a means of compensating for the absorption loss, but the experimental realization of lossless propagation or optical gain in plasmonic waveguides has proven elusive. Here, we demonstrate direct proof of plasmonic propagation with net positive gain over macroscopic distances. The gain is provided by an optically pumped layer of fluorescent conjugated polymer adjacent to the metal surface in a dielectric-metal-dielectric plasmonic waveguide.

Published
2010

14. Coherence and dephasing in self-assembled quantum dots:(invited)

Author

Hvam, Jørn Märcher, Leosson, K., and Birkedal, Dan

Subjects
Condensed Matter::Mesoscopic Systems and Quantum Hall Effect
Abstract

We measured dephasing times in InGaAl/As self-assembled quantum dots at low temperature using degenerate four-wave mixing. At 0K, the coherence time of the quantum dots is lifetime limited, whereas at finite temperatures pure dephasing by exciton-phonon interactions governs the quantum dot coherence. The inferred homogeneous line widths are significantly smaller than the line widths usually observed in the photoluminescence from single quantum dots indicating an additional inhomogeneours broadening mechanism in the latter.

Published
2003

36. Optical anisotropy in vertically coupled quantum dots

Author

Yu, P., primary, Langbein, W., additional, Leosson, K., additional, Hvam, J. M., additional, Ledentsov, N. N., additional, Bimberg, D., additional, Ustinov, V. M., additional, Egorov, A. Yu., additional, Zhukov, A. E., additional, Tsatsul’nikov, A. F., additional, and Musikhin, Yu. G., additional

Published
1999
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45. Dynamic dipole-dipole interactions between excitons in quantum dots of different sizes.

Author

Matsueda, H., Leosson, K., Zhangcheng Xu, Hvam, J.M., Ducommun, Y., Hartmann, A., and Kapon, E.

Abstract

A model of the resonance dynamic dipole-dipole interaction between excitons confined in quantum dots (QDs) of different sizes at close enough distance is given in terms of parity inheritance and exchange of virtual photons. Microphotoluminescence spectra of GaAs-AlGaAs coupled QDs are proposed to be analyzed by this model, including features created by high-speed random switching, depending on the carrier configuration in and around the QD pair, between the dipole-dipole split states and the nonsplit states to give double peaks at both of the QDs. [ABSTRACT FROM PUBLISHER]

Published
2004
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49. Photonic bandgap effect in disordered arrays of scatterers: Implications to broadband, low-loss waveguiding

Author

Leosson, K., Bozhevolnyi, S., Valentyn Volkov, and Boltasseva, A.

Subjects
Physics::Optics
Abstract

We demonstrate waveguiding of surface plasmon polaritons along channels through arrays of randomly located surface scatterers, constituting an amorphous (two-dimensional) photonic "crystal" that exhibits a broader stop-band and lower bend loss than conventional periodic configurations.

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