Radiative coupling in single quantum wells and Bragg structures

Time-integrated four-wave mixing experiments reveal strong influence of the cladding layer thickness dr. its refractive index and the reflectivity of the sample-air interface on the radiative dephasing time T-rad Of excitons in single quantum wells and multiple quantum well structures. A cladding la yer thickness of lambda/2 and lambda/4 decreases and increases, respectivel y, Trad Furthermore, we show that the superradiance is not limited to the h eavy-hole exciton but can be observed even on excited and light-hole-excito n states as well as on correlated electron-hole-pair states. All findings a gree fairly well with solutions of the semiconductor Maxwell-Bloch equation s.