Gigantic excited state optical nonlinearities in one dimensional Mott-Hubbard Insulators

摘要

Ground as well as excited state non-linear optical properties of one-dimensional Mott-Hubbard insulators are discussed in detail One dimensional strongly correlated materials are predicted to have several orders-of-magnitude larger excited state optical non-linearities in comparison to that from the ground state One dimensional strongly correlated materials like Sr^CuOs, halogen bridged Ni compounds etc have excited one- and two-photon allowed states almost energetically degenerate which leads to order(s)-of-magnitude larger dipole coupling between them in comparison to that between the ground and optical state. This causes several orders-of-magnitude enhancement in the optical non-linearities obtained from the first two-photon state in the wavelength region suitable for terahertz communications. Our results and conclusions are based on exact numerical calculations of extended Hubbard model suitable strongly correlated systems We also discuss ground state non-linear properties like third-harmonic generation, two-photon absorption, electro-absorption from the theoretical model and compare with experiments.