Optical limiting mechanisms in fullerene-containing Pi-conjugated organic materials: polyimide and COANP

Mechanisms of the optical limiting effect in the fullerene-doped ?-conjugated organic systems based on polyimide and 2-cyclooctylamino-5-nitropyridine have been studied. Reverse saturable absorption, two-photon absorption, and charge transfer complex formation have been established to be responsible for the limitation of the laser radiation over visible spectral range. The absorption cross-section of the excited state has been determined for complexes based on both systems.