Intraband terahertz emission from coupled semiconductor quantum wells: A model s

2019-10-30 03:41:49

model quantum coupling phonon exciton

责任者: Wei Min Zhang;Meier, T.;Chernyak, V.;Mukamel, S. 单位: Dept. of Chem., Rochester Univ., NY, USA 来源出处: Physical Review B (Condensed Matter)(Phys. Rev. B, Condens. Matter (USA)),1999/07/15,60(4):2599-609 摘要: Intraband emission resulting from the second-order polarization induced by a femtosecond pump field in semiconductor nanostructures is calculated. The two-band model is transformed to the exciton representation, and exciton-phonon coupling represented by arbitrary spectral densities is incorporated into the equations of motion for the relevant exciton variables through Redfield superoperators. Time-resolved coherent and incoherent terahertz radiation as well as the incoherent optical fluorescence are calculated for a one-dimensional model of coupled quantum wells in an external electric field with on-site Coulomb interaction between electrons and holes and an overdamped Brownian oscillator spectral density representing the electron-phonon coupling. A doorway-window picture based on the reduced single-electron density matrix is developed for the analysis of both signals. Disorder and phonon-induced dephasing effects on the various signals are discussed and compared 关键词: fluorescence;interface states;phonon-exciton interactions;semiconductor quantum wells;intraband terahertz emission;coupled semiconductor quantum well;exciton representation;second-order polarization;femtosecond pump field;two-band model;exciton-phonon coupling;arbitrary spectral densities;Redfield superoperators;optical fluorescence;one-dimensional model;on-site Coulomb interaction;overdamped Brownian oscillator spectral density;electron-phonon coupling;doorway-window picture