Simultaneous spectral phase shift characterization in two frequency bands

The precise knowledge of spectral phase shift in various optical elements is crucial for applications with ultrashort pulses. Spectrally resolved interferometry is a versatile, commonly used technique to measure material dispersion. However, the bandwidth of the employed light source limits the spectral region where the phase shift can be determined using this method. In this paper, we introduce a modified version of spectrally resolved interferometry, which enables the reconstruction of the spectral phase shift at the fundamental and the second harmonic wavelengths of the illuminating light source from a single interferogram, and hence doubles the evaluation bandwidth originally available. The presented method is experimentally validated by measuring several dielectric and semiconductor material plates.