Gouy phase shift measurement using interferometric second-harmonic generation

We report on a simple way to directly measure the Gouy phase shift of a strongly focused laser beam. This is accomplished by using a recent technique, namely, interferometric second-harmonic generation. We expect that this method will be of interest in a wide range of research fields, from high-harmonic and attosecond pulse generation to femto-chemistry and nonlinear microscopy. (C) 2018 Optical Society of America.