Abstract-TERA-MIR radiation: materials, generation, detection and applications II

M. F. Pereira
http://link.springer.com/article/10.1007%2Fs11082-015-0146-x

The main objective of MPNS COST ACTION MP1204 is to advance novel materials, concepts and device designs for generating and detecting THz (0.3–10 THz) and Mid Infrared (10–100 THz) radiation using semiconductor, superconductor, metamaterials and lasers. This special edition summarizes part of the progress achieved in the first year of our network by covering a wide range of related topics, e.g. fundamental studies of intervalence THz polaritons and entangled excitons to the design and development of THz and MIR Quantum Cascade Lasers and novel antennas, filters and metamaterials. Spectroscopy and modelling of the interaction of THz radiation with biomatter are investigated. Mid infrared detection and emission are modelled and develped including supercontinuum studies. Relevant results for nitrides, bismides and graphene are discussed covering industrial and academic applications, theory and experiments, illustrating the impact of a synergistic approach to THz and MIR within our TERA-MIR concept.

Abstract-Coupling of THz radiation with intervalence band transitions in microcavities

M. F. Pereira, Jr. and I. A. Faragai  »View Author Affiliations

Optics Express, Vol. 22, Issue 3, pp. 3439-3446 (2014)
http://dx.doi.org/10.1364/OE.22.003439

http://www.opticsinfobase.org/oe/abstract.cfm?uri=oe-22-3-3439

The strong coupling of THz radiation and material excitations can improve the quantum efficiency of THz emitters. In this paper, we investigate THz polaritons and antipolaritons based on valence band transitions, which allow TE coupling in a simple configuration. The approach can improve the quantum efficiency of THz based devices based on TE mode in the strong coupling regime of THz radiations and intervalence bands transitions in a GaAs/AlGaAs quantum wells. A Nonequilibrium Many Body Approach for the optical response beyond the Hartree-Fock approximation is used as input to the effective dielectric function formalism for the polariton/antipolariton problem. The energy dispersion relations in the THz range are obtained by adjusting the full numerical solutions to simple analytical expressions, which can be used for non specialists in a wide number of new structures and material systems. The combination of manybody and nonparabolicity at high densities leads to dramatic changes in the polariton spectra in a nonequilibrium configuration, which is only possible for intervalence band transitions.

© 2014 Optical Society of America

Abstract-Interaction of valence band excitations and terahertz TE-polarized cavity modes

• I. A. Faragai, 
• M. F. Pereira

http://link.springer.com/article/10.1007%2Fs11082-013-9780-3

The strong coupling of THz radiation and material excitations has potential to improve the quantum efficiency of THz devices. In this paper, we investigate a simple structure delivering THz polaritons and antipolaritons based on valence band transitions. The approach can improve the quantum efficiency of THz based devices based on TE mode in the strong coupling regime of THz radiations and intervalence bands transitions in a GaAs/AlGaAs quantum well. A Nonequilibrium Many Body Approach for the optical response beyond the Hartree–Fock approximation is used as input to the effective dielectric function formalism for the polariton/antipolariton problem. The energy dispersions relations in the THz range are obtained based on simplified analytical approximation.