Reflection Z-scan technique for the study of nonlinear refraction and absorption of a single interface and thin film

Abstract

Spatial modification of a Gaussian beam reflected from a single interface and a thin film with intensity-dependent refractive index and absorption coefficient is studied theoretically. The measurement of this modification by different positions of the nonlinear surface with respect to the beam waist (the modified Z-scan technique) can be used to study nonlinear optical properties. For a single interface the measurements permit the nonlinear parameters to be determined unambiguously. For a thin film the multiple internal reflections are important, and the value and the sign of nonlinear refraction and absorption coefficients cannot be uniquely found.