Z-scan measurements of single walled carbon nanotube doped acetylenedicarboxylic acid polymer under CW laser

•The β and n2 of SWNT doped ADC polymer are estimated.•The excited-state absorption cross sections of SWNT doped ADC polymer are calculated at λ=635 nm.•The sign of the n2 is negative.

Z-scan measurements of single walled carbon nanotube (SWCNT) doped with acetylenedicarboxylic acid (ADC) polymer are performed using a CW diode laser at 635 nm wavelength with 17 mW power. The nonlinear absorption coefficient (β), nonlinear refractive index (n2), the real and imaginary parts of the third-order nonlinear optical susceptibility (Re χ3), (Im χ3) of the investigated samples are calculated. It was found that the β values decrease with increase in on-axis input intensity I0. Also, these values are found to be proportional with sample concentrations. The excited-state absorption cross sections were calculated to be at σex=5.08×10−14 cm2 for the (SWCNT) and at 15.1×10−14 cm2 for the ADC polymer. It was found that the σex is larger than ground-state absorption cross sections, indicating that the reverse saturable absorption mechanism (RSA) is the dominating mechanism for the observed absorption nonlinearities.