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Pump Intensity (pump + intensity)

Distribution by Scientific Domains
Physics and Astronomy75%

Selected Abstracts

Up-Conversion Photoluminescence in Polyfluorene Doped with Metal(II),Octaethyl Porphyrins

ADVANCED MATERIALS, Issue 24 2003
P.E. Keivanidis
The up-conversion photoluminescence (PL) in films of polyfluorene (PF) doped with metallated porphyrins is reported for the first time. The dependence of the up-conversion process on the pump laser intensity and wavelength, the central metal moiety of the dopants, and the temperature is presented. Up-conversion emission is observed at pump intensities as low as 2 kW,cm,2. Comparison of the PF integral PL intensities after laser excitation by 532, 543, and 405 nm enables the discussion of the energy-transfer mechanism and the efficiency of the process. [source]

Photoinduced Faraday rotation in the magnetic semiconductor CdCr2Se4

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 4 2004
L. L. Golik
Abstract A growth of the excitonic peak in the absorption spectrum and an enhancement of the Faraday rotation band (approximately 50% of the linear effect value) were induced by intensive radiation of Nd3+ -laser (h, = 1.17 eV) in ferromagnetic phase of magnetic semiconductor CdCr2Se4. The photoinduced effects increased during a pumping pulse and also with growth of pump intensity. In studies of the non-linear Faraday rotation a change of the spectral band shape was observed along with the growth of the rotation angle. The observed effects can be explained by the screening of internal electric fields existing in CdCr2Se4 crystals by photoexcited charge carriers. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Bipolariton laser emission from a GaAs microcavity

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 2 2007
L. M. Moreira
Abstract Biexciton emission properties were studied in a single GaAs quantum well (QW) semiconductor planar microcavity by photoluminescence measurements at low temperatures. At high pump intensity a bipolariton emission appears close to the lower polariton mode. This new mode appears when we detune the cavity resonance out of the lower polariton branch, showing a laser like behavior. Very small linewidths were measured, lying below 110 µeV and 150 µeV for polariton and bipolariton emission respectively. The input/output power (I/O) measurements show that the bipolariton emission has a weaker coupling efficiency compared to previous results for polariton emission. Varying the pump laser polarization, we were able to show the selection rules for the biexciton particle creation in the quantum well. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Photoluminescence and in-plane diffusion of indirect excitons

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 11 2005
L. E. Smallwood
Abstract In-plane spatial diffusion of indirect excitons in GaAs/AlGaAs coupled quantum wells (QWs) is studied theoretically. In spatial photoluminescence (PL) diagrams obtained from experiments, two rings of PL appear around the excitation spot, and their size and intensity depend upon the lattice temperature Tb and the optical pump intensity. We explain and model numerically the first PL ring, by using coupled nonlinear equations for the diffusion, thermalization and optical decay of the excitons. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]