A theoretical investigation of the effects of static disorder on the linear optical response and the degenerate four-wave-mixing signals of multiple quantum well Bragg structures is presented. It is shown that disorder leads to a finite radiative coupling strength of subradiant modes that are optically forbidden in the ideal structure. In the absorption spectrum, the subradiant modes appear as sharp resonances in the presence of barrier thickness fluctuations, whereas the disorder induced subradiant modes are inhomogeneously broadened in the presence of interface roughness. The decay of the time integrated four-wave-mixing signal at large delays is determined by the dephasing time of subradiant modes, whereas the initial fast decay is dominated by the superradiant mode. A free induction decay is observed in the presence of barrier thickness fluctuations. In contract, even a small inhomogeneous broadening induces a photon-echo-like behavior for the subradiant modes, while the superradiant mode still exhibits a free induction decay.
|Original language||English (US)|
|Number of pages||10|
|Journal||Physica Status Solidi (B) Basic Research|
|State||Published - Jan 1998|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics