Ultrafast absorptive and refractive nonlinearities in multiwalled carbon nanotube films

Abstract

The absorptive and refractive nonlinearities in a film of multiwalled carbon nanotubes were investigated using femtosecond laser pulses at a wavelength range from 720 to 780 nm. The absorptive and refractive nonlinearities were found to be of negative and cubic nature in laser irradiance range, as shown by the z-scans. The magnitude of third-order nonlinear susceptibility was found to be about 10-11 esu. The results show that nonresonant negative nonlinearities exhibits relaxationn time of ∼2 ps.