Nonlinear optical response from excitons in soliton lattice systems

Exciton effects on conjugated polymers and the resulting optical nonlinearities are investigated in soliton lattice systems. The magnitude of the THG at the 10 percent doping increases by the factor about 102 from that of the neutral system. The huge increase by the order two is common for several choices of Coulomb interaction strengths, and is seen in open systems as well as in periodic systems. We also find that the THG enhances much larger when the number of solitons is two in the open boundaries. This new fact should be attractive to the experimentalists.