MEAN FIELD APPROACH AND COMPUTER-SIMULATION OF SELF-ORGANIZATION RESULTING IN 2ND HARMONIC-GENERATION IN FIBERS

Qualitative analysis and computer experiment show that self-organization of charge transfer excitons connected to randomly distributed active centers (Ge-centers) results in the appearance of a strong polarization P opposite to the applied field E0 approximately chi-(3)E2-omega-E(omega)*E(omega)* (non-thermodynamic case). A corresponding static electric field E(r) = -4-pi-P(r) follows the rectified field E0(r) and is the reason of the second harmonic generation. In contrast with ordered centers (molecular crystal) the system has no stationary state, it travels in some region near the state found in the mean field approximation.