Phase stability of terawatt-class ultrabroadband parametric amplification. 
The phase stability of broadband (280 nm bandwidth) terawatt-class parametric amplification was measured, for the first time to our knowledge, with a combination of spatial and spectral interferometry.  Measurements at four different wavelengths from 750 to 900 nm were performed in combination with numerical modeling.  The phase stability is better than 1/23 rms of an optical cycle for all the measured wavelengths, depending on the phase-matching conditions in the amplifier.