Photothermal, photoconductive and nonlinear optical effects induced by nanosecond pulse irradiation in multi-wall carbon nanotubes

The influence of the optical absorption exhibited by multi-wall carbon nanotubes on their photothermal, photoconductive and nonlinear optical properties was evaluated. The experiments were performed by using a Nd:YAG laser system at 532 nm wavelength and 1 ns pulse duration. The observations were carried out in thin film samples conformed by carbon nanotubes prepared by an aerosol pyrolysis method; Raman spectroscopy studies confirmed their multi-wall nature. Theoretical and numerical calculations based on the heat equation allow us to predict the temporal response of the induced effects associated to the optical energy transference. A two-wave mixing method was employed to explore the third order nonlinear optical response exhibited by the sample. A dominant thermal process was identified as the main physical mechanism responsible for the optical Kerr effect. Potential applications for developing a monostable multivibrator exhibiting different time-resolved characteristics were analyzed.