Optimal Control of the Elliptically Polarized Attosecond Pulse Generated by Two-color Polarization Gating Using Bayesian Optimization

We present an efficient high-order-harmonic optimal control scheme for the generation of an for the generation of an isolated ultrashort elliptically polarized attosecond pulse in gases with a two-color polarization-gating. The optimal control scheme is implemented using Bayesian Optimization. For illustration, the high-order-harmonic generation (HHG) of a Helium atom is considered for optimization. It is shown that optimally shaped laser waveforms can greatly enhance the difference between the right circularly polarized component of the HHG and the left one and extend the HHG plateau that can generate an isolated ultrashort elliptically polarized attosecond pulse efficiently. Moreover, by performing a Monte Carlo classical trajectory study and a detailed wavelet time-frequency analysis, the detailed mechanism responsible for the HHG processes is revealed and the optimized harmonics corresponding to the short-trajectory electrons are responsible for an isolated ultrashort 53-as pulse.