Investigation of the phase of the second-order susceptibility measured in off-resonant surface second-harmonic generation

Relative measurement of the phase of the surface second-order susceptibilit y is shown to be easily obtained in a surface second-harmonic generation ex periment by inserting a quarter-wave plate on the fundamental and measuring the second-harmonic intensity vs. the fundamental ellipticity. This techni que is applied to two samples: an isotropic surface of chiral molecules and a calcite crystal. In both cases, a dephasing between the different suscep tibility components is observed.