Generation of few-cycle laser pulses at 2 μm with passively stabilized carrier-envelope phase characterized by f-3f interferometry

Abstract

We report on generation and characterization of few-cycle laser pulses with the central wavelength of 2 μm at repetition rate of 50 kHz. The source is based on noncollinear parametric amplification and difference frequency generation leading to passively stabilized carrier-envelope phase (CEP). CEP is characterized using f-3f technique based on spectral interference between the fundamental spectrum broadened via self-phase modulation and the third harmonics, which are both generated by tight focusing of the pulses to gallium gadolinium garnet (GGG) crystal. We demonstrate the capability of this technique for CEP measurement and long-term stabilization. Further we show that the pulses can be compressed to a duration of 1.7 optical cycles after spectral broadening in the GGG crystal.