Abstract

Transient spectroscopy like four-wavemixing and pump-probe techniques with femtosecond- time resolution are powerful techniques to study ultrafast coherent excitan dynamics in semiconductor systems. Considerable efforts were spent on investigations of quantum beats, their coherence properties, and relaxation dynamics.¹ However, the interpretation of the data usually neglected the spatial extension and dispersion of the excitan, arguing with the use of thin samples. Since polariton formation is inherently connected with optical excitation of the excitan, it is of great importance for femtosecond experiments in bulk material and quantum wells (QWs), e.g., in four- wave-mixing experiments.^2,3

© 1996 Optical Society of America