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Location:Room 22a, 2nd floor, ICM Light Engineering and Optofluidics
14:30 - 15:00
Determination of the Diffusion Parameters of an Optically Thin Scattering Sample Through Time-resolved Transmission
Mehdi Aas1, Wilbert L. IJzerman2, Gilles Vissenberg2, Willem L. Vos1, Ad Lagendijk1
1Complex Photonic Systems (COPS), MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, Enschede 7500 AE, The Netherlands; 2Philips Lighting, High Tech Campus 44, Eindhoven 5656 AE, The Netherlands
The color-converting phosphor diffusers in white LEDs are optically thin and hence are hard to characterize. We show that separating of direct from diffuse transmission in time-resolved experiments results in less than 20% error in determining the diffusion parameters using the diffusion approximation.
15:00 - 15:30
Light scrambling in non-circular multimode fibers
Ralf Hambach1,2, Martin Weigert3, Herbert Gross1,2
1Friedrich-Schiller-Universität Jena, Institute of Applied Physics, 07743 Jena, Germany; 2Fraunhofer Institute of Applied Optics and Precision Engineering, 07745 Jena, Germany; 3Max Planck Institute for Cell Biology and Genetics, 01307 Dresden, Germany
Using geometrical and wave optical simulations, we investigate scrambling of light in
long multimode step-index fibers. Using an analogy with mathematical billiards, nonstandard fiber geometries are proposed to increase the scrambling efficiency. Our predictions are verified by corresponding simulations.
15:30 - 16:00
Recombination and stimulated emission in InAs-based LED heterostructures
Karim Mynbaev1,2, Nikolay Bazhenov2, Antonina Semakova1,2, Ekaterina Bykhanova1,2, Nikolay Stoyanov3, Anton Сhernyaev3, Sergey Kizhaev3
Results of the studies of electroluminescence of InAs-based LED heterostructures with active layer made of InAs(Sb) epitaxial films or InAs(Sb)/InAsSb(P) quantum wells in the temperature range 4.2–300 K are reported on. In the course of the studies, we were able to follow the effect of various recombination mechanisms, and to observe stimulated emission from LED heterostructures, – with optical resonator presumably formed normal to the growth plane. Prospects of increasing efficacy of LEDs operating in the middle infrared wavelength range will be discussed as well as possibilities of using the heterostructures for the fabrication of vertical surface-emitting lasers.