Passively CEP Stable Sub-2-cycle Source in the Mid-Infrared by Adiabatic Difference Frequency Generation

We report on the generation of a passive carrier-envelope phase (CEP) stable 1.7-cycle pulse in the mid-infrared by adiabatic difference frequency generation. With sole material-based compression, we achieve a sub-2 cycle 16 fs pulse at a center wavelength of 2.7 μm and measured a CEP stability of <190 mrad RMS. The CEP stabilization performance of an adiabatic downconversion process is characterized for the first time.