Measurement of nonlinear absorption and refraction in titanium dioxide single crystal by using a phase distortion method

A phase distortion method is applied to examine the optical nonlinearity in titanium dioxide single crystal. The two‐photon absorption coefficient obtained agrees with that reported previously, while the nonlinear index of refraction is larger than that predicted theoretically by a factor of 10. One of the reasons for the discrepancy is given as the applicable limit of the simple theory in which a two‐parabolic band model has been assumed in the analysis.