Nonresonant n2 and TPA coefficient measurement in polymer waveguides by different measurement techniques

Nonlinear optical waveguide elements have to be operated at wavelengths where the waveguide material exhibits minimum linear alpha and higher-order alpha(2) absorption parameters and where the nonlinear refractive index parameter n(2) is as large as possible. The dispersion of these two quantities has been measured in the wavelength range between 780 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 pulses. The measurements have been performed on one class of conjugated polymers, substituted poly(phenylene-vinylene) (PPV), which are promising candidates for the demonstration of nonlinear switching in waveguide 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 demonstrated. The nonresonant n(2) values are several times 10(-14) cm(2) W-1 for the two PPV derivatives measured. Spatial solitons have been observed for the first time in a polymer waveguide.