Linear and nonlinear optical properties of a ladder poly(p-phenylene) polymer

Linear and nonlinear optical properties of a ladder polymer based on the poly(p-phenylene) backbone (LPPP) have been investigated. Femtosecond degenerate four-wave mixing (DFWM) was used for the determination of the nonlinear refractive index n2 at 800 nm. Values of ‖n2‖ = (3–7) × 10−13 cm2/W were obtained from DFWM measurements on thin films and solutions of the polymer. The two-photon absorption coefficient of LPPP is estimated to be β=5×10−9 cm/W at 800 nm.