• Optical bistability;
  • Molecular aggregates;
  • Dipole–dipole interaction


The possibility of mirrorless optical bistability in molecular aggregates with dipole–dipole interaction was studied theoretically. Dimers and ordered layers of the Langmuir–Blodgett type or J-aggregates consisting of identical polyatomic fluorescent molecules were chosen as molecular aggregate models. The investigation was carried out on the basis of the Bogolubov equation chain for the density matrix of molecular aggregates and its components. It is shown that the fluorescence intensity and absorption ability are described by bistable and hysteresislike behaviour when the parameters of the molecular aggregate and pumping radiation are chosen suitably. An analysis of the bistability mechanism in such aggregates is given. Possibilities of controlling one light beam by another and switching polychromatic light flow by using a bistable device based on molecular aggregates are discussed.