Nonlinear optical absorption and reflection of single wall carbon nanotube thin films by Z-scan technique

Both the nonlinear optical transmission and reflection characteristics of HiPco-based single wall carbon nanotube (SWNT) thin films are studied by using the Z-scan method with femtosecond laser pulses at a wavelength of 1.46 mu m. The nonlinear absorption coefficient and nonlinear refractive index are obtained as (5.4 +/- 2.0) x 10(-7) cm/W and (1.1 +/- 0.5) x 10(-11) cm(2)/W, respectively, which are considerably greater than those of other optical materials. This large optical nonlinearity is ascribed to (a) homogeneously deposited thin nanotube film on optically transparent barium fluoride, (b) just-resonant excitation condition, and (c) intrinsic saturable absorption feature of SWNTs. (C) 2008 American Institute of Physics.