24-25 January, 11:00am in Institute of Radiophysics and Electronics of NASU, Council room (3 floor)
Prof. Mauro F. Pereira,
Sheffield Hallam University, Materials and Engineering Research Institute
Research interests: Nonlinear and quantum optics, exciton and polariton effects, band structure engineering, many-body effects, semiconductor lasers (including quantum cascade structures), nonequilibrium Greens functions and numerical methods.
Short Biography: Mauro F. Pereira was born in Rio de Janeiro, Brazil and received the BSc in Physics at PUC/RJ in 1983 and the MSc in Physics in 1985. He completed the PhD in Optical Sciences at the Optical Sciences Center in Tucson/AZ in 1992 and received an equivalent Dr. Sci. degree in Physics from UFRJ in 1993. He was a Research Associate at PUC/RJ, CBPF, Uni-Rostock, and the TU-Berlin, an Invited Lecturer in Bremen, an Associate Professor at UFBA and a Senior Researcher at Tyndall National Institute before joining the Materials and Electrical Engineering Research Institute of Sheffield Hallam University as a Professor where he holds the Chair of Theory of Semiconductor Materials and Optics.
Lecture 1. Thursday 24.01.2008, 11:00 am
Optical Engineering for the 21st Century: Microscopic Design of Semiconductor Lasers
In the beginning of the 20th Century an electrical engineer or applied physicist would go very far by using simple expressions like voltage = resistance × current. However as the century evolved electronics progressed into micro electronics to nano electronics and optoelectronics and now sophisticated simulation methods are required to create new advanced devices. Devices that were part of science fiction like lasers are now on our every day life. In this talk I will start with the basic principle of operation of semiconductor lasers and then describe in simple terms how laser light can be generated in a semiconductor device at nanoscale. I will then compare and contrast conventional interband optics with intersubband optics and the frontier of microscopic design of semiconductor lasers: the quantum cascade laser. Results of our state of the art device simulator will be presented and the difficulties to create new mid infrared and THz devices will be explained. These are the most complex structures ever grown in a laboratory and some of them already have commercial applications. The need for advanced quantum statistical mechanics, many particle and nonequilibrium Physics to describe these devices will be explained.
Schematic view of a typical edge emitting semiconductor laser
Lecture 2. Friday 25.01.2008, 11:00 am
Controlling bosonic effects in light intersubband-excitation coupling in nanostructures
Excitons and polaritons play a major role in interband optics and since in the last decade semiconductor optics has been steadily evolving towards the less explored field of intersubband transitions, it is of general interest to understand how light couples with an intersubband excitation. A recent theory predicted the possibility of intersubband polaritons for oblique incidence by means of a cavity created by total internal reflection at the air interface. Indeed the microcavity polarity splitting of intersubband transitions has been observed experimentally. Stimulated by the striking good agreement between theory and experiments, a Hamiltonian approach based on a bosonic approximation for the intersubband excitation has been developed to treat the quantum vacuum properties of the interusbband cavity polariton field. However, this paper demonstrates that the coupling between light and intersubband excitations in semiconductors is fundamentally different from the well understood coupling to interband transitions that leads to excitonic polaritons and a more general intersubband antipolariton concept is introduced.
Intersubband antipolariton dispersion relations of a 2.9 μm microresonatorwith a GaAs/AlGaAs core as a function of incidence angle