Near infrared nonlinear refractive index dispersion of metallic and semiconducting single-wall carbon nanotube colloids

Third-order nonlinear optical properties of different colloidal systems containing metallic and semiconducting enriched single wall carbon nanotubes have been investigated. Thermally managed Z-scan technique was performed to measure the nonlinear refractive index (n2) and estimate the absorption coefficient (β) of the colloidal systems. The n2 dispersion curve was obtained for both colloids in the range of 755–825 nm, showing a considerable increase on the nonlinear refractive index for laser tuned at 800 nm. The measurements also showed that the colloids nonlinear absorption coefficients were smaller than 8.5 × 10−10 cm/W in this wavelength range. Analysis of the obtained figures of merit indicates that these systems are promising materials for all-optical switching applications.