A laser beam irradiating a semiconductor in its transparency region induces a splitting of the exciton line through the dependence of the optical Stark effect on the different transition matrix elements. The splitting is observed in bulk and multiple-quantum-well GaAs, by femtosecond time-resolved spectroscopy for various polarization configurations. Experimental results are in good agreement with theory.

• Received 12 April 1988

DOI:https://doi.org/10.1103/PhysRevLett.62.74