Second-harmonic generation pulse splitting in quartz observed by frequency-domain interferometry

Abstract

Second-harmonic generation from a thin quartz wedge is studied using short laser pulses. Under phase mismatched condition a temporal splitting of the second-harmonic field occurs due to the different group velocities of the free and forced modes. By measuring the temporal splitting as a function of the quartz crystal thickness using spectral interference a non-zero time-difference between the two second-harmonic pulses at the incident surface is predicted. This is interpreted as a phase-difference between the homogeneous and the inhomogeneous solution of the wave equation at the incident surface.