Midinfrared third-harmonic generation from macroscopically aligned ultralong single-wall carbon nanotubes

We report the observation of strong third-harmonic generation from a macroscopic array of aligned ultralong single-wall carbon nanotubes (SWCNTs) with intense midinfrared radiation. Through power-dependent experiments, we determined the absolute value of the third-order nonlinear optical susceptibility chi((3)) of our SWCNT film to be 5.53 x 10(-12) esu, three orders of magnitude larger than that of the fused silica reference we used. Taking account of the filling factor of 8.75% for our SWCNT film, we estimate a chi((3)) of 6.32 x 10(-11) esu for a fully dense film. Furthermore, through polarization-dependent experiments, we extracted all the nonzero elements of the chi((3)) tensor, determining the magnitude of the weaker tensor elements to be similar to 1/6 of that of the dominant chi((3))(zzzz) component. DOI: 10.1103/PhysRevB.87.161405