tel: +44 114 225 5312
E-mail:
m.pereira@shu.ac.uk
Area of Expertise
Nonlinear and quantum optics, quantum transport, exciton and polariton effects, band structure engineering, many-body effects, semiconductor lasers (including quantum cascade structures), photo and thermophotovoltaic devices, nonequilibrium Greens functions and numerical methods.
Biography
Mauro F. Pereira was born in Rio de Janeiro, Brazil and received the BSc and MsC in Physics at PUC/RJ. He completed the PhD in Optical Sciences at the Optical Sciences Center in Tucson/AZ and received an equivalent Dr. Sci. degree in Physics from UFRJ. 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. He has over 80 journal and proceedings publications and has been elected a Fellow of SPIE in 2011 for achievements in theory of semiconductor materials and optics.Lecture Title(s)
Introduction to Semiconductor Optics
This lecture starts from a very simple classical oscillator model, and evolves to basic semiconductor band structure and optical transitions for both bulk and quantum well devices. More advanced treatment for semiconductor materials (semiconductor Bloch equations and nonequilibrium Greens Functions) and the basic physics governing light emission in Light Emitting Diodes and Semiconductor Lasers are also discussed. A clear connection between simple models and the more advanced simulation methods currently used are given as well as ample reference to simulation software available in the market are given. Examples from our semiconductor material simulation capabilities and how our codes have been used for recent device development and characterization in Europe are provided.
Terahertz and Mid Infrared Sources, Detection and Applications
THz and MIR radiation (TERA-MIR) can be transmitted through nearly any material without causing biological harm. I will give a summary of present and near future biomedical applications on diagnostics and therapy and show science fiction has somehow inspired some of the future applications like MIR breath analysis. A review of the State of the Art on TERA-MIR detection and applications will be given next. The effort to develop Quantum Cascade Lasers will be summarized. However other alternative to THz QCLs will also be presented, e.g. THz Difference-frequency Generation in Quantum Cascade Lasers (generating THz from efficient MIR QCLs), Sub-Terahertz Imaging From Avalanching GaAs Bipolar Transistors, mm-Wave Signal from hase-Locked DFB via Four Wave Mixing, Josephson Junctions as THz sources, Clinotrons as THz sources, Semiconductor materials for pulsed THz sources, Superconducting THz electronics with Josephson vortices and even carbon nanotubes. Furthermore detailed studies of fundamental physics related to intersubband optics (e.g. intersubband polaritons will be presented). Metamaterials will also be discussed in both millimiter wave and THz ranges. Due to the increasing demand for bandwidth it is expected that THz communication systems will be developed in a few years time. I will close the review by summarizing current work towards THz communications and corresponding challenges.
21st Century Optical Engineering: Microscopic Designing 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. 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. 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. Both technological and mathematical/simulations issues will be addressed and the role of complex scattering mechanisms will be explained. It will be further demonstrated how we can now visually study the nonequilibrium charge distribution in the structure and use it to analyse potential design failures and re-design the lasers based on those studies. I will close the talk by showing how our new prototype commercial simulator bridges the gap between advanced quantum mechanics and user-friendly software developments.
Elementary excitations and new interubband quasiparticles
This lecture starts with an overview of the quasiparticle concept and illustrations. Next the couplimg of light with material excitations is discussed. 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 lecture 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. Different applications of the concept are discussed for both quantum wells and cascade laser structures and numerical results are shown for both interband and intersubband cases.
