Abstract
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.
Highlights
THz wave photonics has attracted strong interest in the last few years due to innumerous applications within science and in practical devices for imaging, medical applications and safe security scans
Hhigh emission efficiency has been demonstrated for polaritonic states in the ultra strong coupling regime, with electroluminescence peaks visible at cryogenic and room temperature, constituting the first THz range intersubband electroluminescence observed at room temperature [10]
The microscopic approach presented here unique features not found in the literature so far: (i) The valence bands are investigated opening new possibilities for polaritonic devices; (ii) Intervalence-band transitions in the transverse selectric (TE) mode are investigated in contrast to the majority of work in the literature, focused on TM-mode inter-conduction band transitions(iii) Full nonequilibrium many body solutions for the intersubband susceptibility problem with electron-electron scattering included beyond the Hartree-Fock approximation [12, 13] and valence band nonparabolicity are used as starting point and are adjusted to a simple model that can be used by researchers not trained in the numerical solution of microscopic nonequilibrium Green's functions methods
Summary
THz wave photonics has attracted strong interest in the last few years due to innumerous applications within science and in practical devices for imaging, medical applications and safe security scans. The microscopic approach presented here unique features not found in the literature so far: (i) The valence bands are investigated opening new possibilities for polaritonic devices; (ii) Intervalence-band transitions in the TE mode are investigated in contrast to the majority of work in the literature, focused on TM-mode inter-conduction band transitions(iii) Full nonequilibrium many body solutions for the intersubband susceptibility problem with electron-electron scattering included beyond the Hartree-Fock approximation [12, 13] and valence band nonparabolicity are used as starting point and are adjusted to a simple model that can be used by researchers not trained in the numerical solution of microscopic nonequilibrium Green's functions methods This gives a high potential for impact of this work for research in different research fields and applicability to new materials. This paper is organized as follows: Section 2 shows the main equations and summarizes the mathematical method used; numerical results are given in given in Section 3, which is followed by a brief summary
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