Many‐Body Theory for the Dense Exciton Gas of Direct Semiconductors. III. Response of the Many‐Exciton System on an Externally Driven Light Field

Abstract

on the occasion of his 80th birthdayThe nonlinear response of a dense exciton gas in a platelet on an externally driven field is discussed using non equilibrium Green's function technique. A generaliz,ed Boltzmann-equation of excitons containing many-particle corrections in the diffusion-, drift-and collision-term is derived. Using a relaxed distribution (Boltzmann-distribution) and an unrelaxed distribution (macro-occupation) of Is-excitons a bistability in exciton density as well as in the transmitted light intensity is obtained for a nearly resonant and stationary applied pump-field of intensity 0.1 and 10 kW/cm2, respectively. The bistability is obtained as a pure excitonic effect below the Mott-transition.

Dipolar Coupling at Interfaces of Ultrathin Semiconductors, Semimetals, Plasmonic Nanoparticles, and Molecules

“…To describe excitonic screening, principle value integrals in the scattering contribution could be summed up to provide excitonic screening. [ 88–90 ] The main effect of screening would be a reduction of the interaction strength between and in the layers. We arrive at the excitonic Bloch equation [ 82,86,91 ] …”

Light Transmission at the 1s‐Exciton Resonance of CdS in the Presence of a Density Profile of Excitons

“…Since we consider a situation where the high density of excitons is not realized by the transmitted field (test field) itself, we start our calculations with the material equation which connects the dielectric displacement and the electric field strength in the optically linear but nonequilibrium case (see also (10) of [15])…”

“…(kco, rt) .The above change t o the new set of arguments (kto, r t ) leads to differential operators in the exponent as in the general case of nonequilibrium Green's-function technique (see [ 161). The dielectric tensor containing excitonic polarization contributions reads (see also (11) of[15])…”