Generation of 2 μm few-cycle laser pulse with dual laser filaments nonlinear processes

For the first time, we propose a new scheme for generating few-cycle 2 μm seed laser pulse in an optical parametric chirped pulse amplifier (OPCPA) front-end. The 2 μm ultrafast seed laser pulse is generated via a difference frequency generation (DFG) process between the visible and near-IR supercontinuum from two different filamentation processes inside the transparent YAG crystals. The generated DFG pulse spectrum has a broad spectrum range of 1200 nm from 1500 nm to 2700 nm. By further scaling up the pulse energy of the seed laser pulse via a non-collinear optical parametric amplification (OPA) stage, the single pulse energy is boosted to 15.6 μJ. After dispersion compensation, the pulse duration is compressed to 14.3 fs with its spectrum covering from 1600 nm to 2600 nm.