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Mon., March 8, 2010, 11a.m. NSERL 3.204














“Manipulating Light Propagation in Bragg-Spaced Quantum Well Structures”
Wesley Johnston, University of Iowa

Resonant photonic bandgap (RPBG) materials are unique photonic structures wherein a series of optical resonances are arranged periodically with frequency of spacing one half of the optical resonance frequency. The variation in the complex susceptibility (index and absorption) of the material gives rise to a photonic bandgap with an intermediate band in the structure, and an associated reflection stopgap. In addition to their unique linear photonic structure, these materials can also display large ultrafast nonlinearities, which can be used to manipulate their photonic band structures. This seminar will discuss experimentally exploiting these nonlinear properties to investigate all-optical polarization switching and tunable optical buffers (i.e., slow light) in a model RPBG system composed of large numbers of periodically arranged quantum wells known as Bragg-spaced quantum wells.

Wesley Johnston holds a bachelor’s degree in physics from Harding University and is pursuing his PhD in physics at the University of Iowa in Iowa City. He is part of the university’s Prineas Group, which is pursuing experimental work in the areas of optoelectronics and photonics, nonlinear optics, MBE growth of III-V compound semiconductors and ultrafast spectroscopy of semiconductors.