Second harmonic generation spectroscopy using broad bandwidth femtosecond pulses.

摘要

A new technique has been developed for the parallel acquisition of second harmonic generation spectra utilizing broad bandwidth femtosecond pulses. A theoretical analysis of the effects of the broad spectral bandwidth on the interpretation of these spectra is constructed and limits are identified in which this constitutes a robust measurement of material properties through normalization by a standard. The influence of pulse chirp on the raw spectra is quantified for non-resonant and resonant pulses. A complimentary technique is developed for measurement of phase spectra through frequency domain interferometry. The new techniques are demonstrated experimentally on the Si/SiO₂ interface and Si_1−xGe _x/SiO₂ interface and compared to the previous technique of narrow bandwidth second harmonic generation spectroscopy.