High-order nonlinear interferometry at Si[110] buried interface

Summary form only given. Second-harmonic based nonlinear-optical interferometry is a technique to measure a phase of nonlinear susceptibility in addition to its absolute value that can be obtained from the SHG intensity measurements. Phase information is important particularly in the vicinity of electron transition. In this case the phase of nonlinear susceptibility can take the value in the range of 0/spl divide/2/spl pi/, changing the phase relations between SH fields generated by different sources, and therefore the total SHG signal. Even in the range of transparency the sign of the susceptibility that is measured by the SHG interferometry is important in case of several nonlinear sources contributing to the SHG signal. We report here the results of the first observation of the third-harmonic and fourth-harmonic interferometry at the Si[110] surface.