NONRESONANT N(2) AND TPA COEFFICIENT MEASUREMENT IN POLYMER WAVE-GUIDES BY DIFFERENT MEASUREMENT TECHNIQUES

Nonlinear optical waveguide elements have to be operated at wavelength s where the waveguide material exhibits minimum linear alpha and highe r-order alpha(2) absorption parameters and where the nonlinear refract ive index parameter n(2) is as large as possible. The dispersion of th ese two quantities has been measured in the wavelength range between 7 80 and 990 nm. A stable semi-integrated Mach-Zehnder interferometer as well as a spectral broadening set-up were used. The light source was an Ar-pumped tunable Ti:sapphire laser, generating picosecond light pu lses. The measurements have been performed on one class of conjugated polymers, substituted poly(phenylene-vinylene) (PPV), which are promis ing candidates for the demonstration of nonlinear switching in wavegui de elements. Low-loss waveguides (<1 dB cm(-1)) with extreme stability against pulsed optical intensity (up to 16 GW cm(-2)), allowing for a nonlinear induced phase shift of more than 3 pi, have been demonstrat ed. The nonresonant n(2) values are several times 10(-14) cm(2) W-1 fo r the two PPV derivatives measured. Spatial solitons have been observe d for the first time in a polymer waveguide.