Feature

Optical Nonlinearities of Quantum-Confined Excitons in Semiconductor Microcavities

F. Jahnke, M. Kira, and S.W. Koch, Dept. of Physics and Material Sciences Center, Philipps-Univ. Marburg, Marburg, Germany, and G. Khitrova and H.M. Gibbs, Optical Sciences Center, Univ. of Arizona, Tucson, Ariz.

Radiatively coupled excitons in quantum wells and microcavities show many properties similar to atoms in the micromaser. For example, excitonic normal-mode coupling resembles vacuum-field Rabi oscillations and effects of radiative coupling between excitons in multiple quantum wells are similar to superradiance of atoms. However, the physical nature of the effects is different. For effects involving few atoms, the quantum properties of the light are important. Reflection, transmission, and absorption experiments in semiconductor microcavities can be described within a semi-classical theory. Also, measurements of the number of photons necessary to see nonlinear effects indicate that current semiconductor experiments are far from the quantum statistical limit, so that interpretations based on quantum ladders, as in Reference 3, are not appropriate. The saturation mechanisms in atoms (e.g., power broadening or local field effects) are completely different from those in semiconductors (phase space filling and Coulomb interaction between carriers).