Colloquium: Rolf Binder

    Thursday, March 26, 2015 - 3:30pm - 5:00pm
    Meinel 307

    "Help, There Is a Zebra in the Quantum Fluid!"


    The interactions between excitons in GaAs quantum wells yield a wide variety of nonlinear optical effects. In this talk, I will focus on the quantum fluid formed by exciton polaritons in a semiconductor microcavity. Nonlinear processes such as four-wave mixing can lead to instabilities and spatial pattern formation. Examples of near-field patterns include stripes and hexagonal lattices, corresponding to 2-spot and 6-spot patterns in the far field. In agreement with our theoretical predictions, our experimental collaborators have observed various patterns, including those corresponding to stripes in the polaritonic quantum fluid density (and no, it's not really a zebra!). We believe that the control of such patterns can lead to new photonic devices, for example polaritonic all-optical switches and transistors. As an aside, I will also briefly discuss the interband dipole matrix element, which is an integral part of exciton physics, and which to this day causes much confusion in the semiconductor community.

    Speaker Bio(s): 

    Rolf Binder is a professor at the University of Arizona, with joint appointments in the College of Optical Sciences and the department of physics. He studied physics at the universities of Dortmund and Stuttgart in Germany. He received his Ph.D. in theoretical physics from the University of Dortmund in 1988 and joined the University of Arizona in 1989. Using a variety of theoretical formalisms, including nonequilibrium Green's functions, his research focuses mainly on the analysis and application of optical properties of solids. Examples of recent research projects include electromagnetically induced transparency, slow and fast light effects in semiconductors, nonlinear spectroscopy and all-optical switching applications of Bragg-spaced multiple quantum wells, optical refrigeration of semiconductors, optical four-wave mixing instabilities in semiconductor quantum wells systems, including microcavities, optical and elastic properties of semiconductor nanomembranes, and optical properties of graphene.