Frequency-domain interferometric second-harmonic spectroscopy

We report a new spectroscopic technique to measure simultaneously the inten sity and the phase of second-harmonic (SH) radiation over a broad spectral range without laser tuning. Temporally separated SH pulses from two sources , excited by the same broad-bandwidth 15-fs Ti:sapphire fundamental pulse, interfere in a spectrometer to yield frequency-domain interference fringes. We demonstrate the technique by measuring the strongly bias-dependent phas e of SH radiation from a Si/SiO2/Cr metal-oxide-semiconductor capacitor in the spectral range of the Si E-1 critical point. (C) 1999 Optical Society o f America.