Femtosecond Z-scan measurement of the third order nonlinear optical coefficient of CuPc thin film

Abstract

The third order nonlinear refractive index and absorption coefficient of copper-phthalpcyanine (CuPc) thin film were measured by Z-scan method in ultrafast time regime. By changing pulse separation, we found that the nonlinear absorption behavior is different for the different pulse repetition rate. At 4MHz, the film exhibits RSA (reverse saturable absorption), while at 800kHz and 400kHz it shows SA (saturable absorption). Also the nonlinear refractive index is found to be different at 4MHz and other repetition rates. © 2001 Taylor and Francis, Inc.