Christian Tanguy

Complex dielectric constant of two-dimensional Wannier excitons

The complex dielectric constant of 2D Wannier excitons is calculated analytically, with the contributions of all bound and unbound states taken exactly into account. This expression may be helpful as a limiting case for quantum well structures, and for the description of the optical properties of saddle-point excitons, including an improved treatment of dispersion effects.

Coulomb correlations to the induced gain in the optical Stark effect of semiconductors

Induced gain may appear when a semiconductor is submitted to an intense monochromatic pump beam tuned below the exciton resonance. Because of the Coulomb interaction between excitons, the gain coefficient strongly departs from the dressed-atom value to which it reduces in the limit of very large detunings. We give the leading corrections to the large detuning expansion, in the case of two and three dimensions.