Ultrabroadband self-phase-stabilized pulses by difference frequency generation

In this work we perform collinear difference frequency generation (DFG) between pulses generated by two synchronized non-collinear optical parametric amplifiers (NOPAs), sharing the same carrier-envelope phase (CEP) since they are seeded by replicas of the same pulse. To investigate self-phase-stabilization of the difference frequency (DF) pulses, we set up a nonlinear spectral interferometer: the DF pulses are focused on a 2-mm frequency-doubling BBO crystal and the spatially overlapped Fundamental Frequency (FF) and Second Harmonic (SH) are directed to the spectrometer through a polarizer.