Light-absorption effect on Bragg interference in multilayer semiconductor heterostructures

The transfer matrix method has been employed to study the effect of light absorption on optical spectra of GaAs/AlAs Bragg reflectors. Substantial distortion of the Bragg plateau due to the absorption in GaAs layers is found. The saturation value of the reflection coefficient of the infinite Bragg reflector is shown to change nonmonotonically with the absorption coefficient showing a minimum. The particular case of low-temperature light reflection from the Bragg mirror in the vicinity of the exciton resonance frequency in GaAs layer is considered. The dramatic enhancement (by a factor of 50) of the exciton resonance amplitude in comparison with the reflectivity spectrum of GaAs is found in case of GaAs/AlAs Bragg structure covered by lambda/2-thick GaAs caplayer. (C) 1996 American Institute of Physics.