Abstract

Z-scan is nowadays the most popular technique to investigate the nonlinear refractive index n₂of different materials. There are several variations of this technique that enables to explore different aspects of the material nonlinear behavior like transient techniques, which are very useful to eliminate parasitic linear effects and to distinguished different contributions (Kerr, thermal contributions, etc.). We now introduce a single beam technique to measured the nonlinear spectral lineshape of a relative narrow absorption line. This is done by placing the sample at either peak or valley position (z = ± z_o) and measuring the signal dependence on laser wavelength. Besides its simplicity and high sensitivity, nonlinear refraction is an interesting technique due to its ability to distinguished the real ${\text{n}}_2^{\cdot }\left(\text{ω}\right)$ and imaginary ${\text{n}}_2^{\cdot \cdot }\left(\text{ω}\right)$ spectra.

© 1996 IEEE