Non-Linear Effects and Coherence Phenomena in Optical Pumping

V. L. Jacobs

V. L. Jacobs

V. L. Jacobs

J. Brossel

Yu. I. Balkareǐ, Alexander S. Cohen, Vladimir S. Posvyanskii

Instabilities of a coherent state of Wannier-Mott excitons sustained by a resonant pumping wave in cavity and cavityless cases are analysed. In particular, instability with respect to spatially periodic stratification can exist. The period of such stratification is L approximately L ex =(h(cross)/m gamma ) 1 2/, where m is the effective exciton mass, and gamma is the reciprocal exciton lifetime. The results of numerical modelling of corresponding non-linear structures are presented. For 'exciton-pumping' bistability, non-monotonic switching fronts are demonstrated numerically.

V. L. Jacobs

Linear and non-linear interactions in electromagnetically induced transparency and related pump-probe optical phenomena involving moving many-electron atomic systems are investigated using a reduced-density-matrix approach. Time-domain (equation-of-motion) and frequency-domain (resolvent-operator) formulations are developed in a unified manner. The standard Born (lowest-order perturbation-theory) and Markov (short-memory-time) approximations are systematically introduced within the framework of the general non-perturbative and non-Markovian formulations. A preliminary semiclassical perturbation-theory treatment of the electromagnetic interaction is adopted. However, it is emphasized that a quantized-electromagnetic-field approach is essential for a self-consistent quantum-mechanical formulation. Our primary result is the derivation of compact Liouville-space operator expressions for the linear and the general (n'th order) non-linear macroscopic electromagnetic-response tensors. These expressions can be evaluated for coherent initial atomic excitations and for the full tetradic-matrix form of the Liouville-space self-energy operator representing the environmental interactions in the Markov approximation. Collisional interactions between atoms can be treated in various approximations for the self-energy operator, and the influence of Zeeman coherences on the electromagnetic-pulse propagation can be investigated by including an applied magnetic field on an equal footing with the electromagnetic fields.