Control of Harmonic Generation by the Time Delay Between Two-Color, Bicircular Few-Cycle Mid-IR Laser Pulses

We study control of high-order harmonic generation (HHG) driven by time-delayed, few-cycle $\omega$ and $2\omega$ counter-rotating mid-IR pulses~[1]. Our numerical and analytical study shows that the time delay between the two-color pulses allows control of the harmonic positions, both those allowed by angular momentum conservation and those seemingly forbidden by it. Moreover, the helicity of any particular harmonic is tunable from left- to right-circular without changing the driving pulse helicity. The highest HHG yield occurs for a time delay comparable to the fundamental period $T=2\pi/\omega$. \\ \noindent[1]~M.V. Frolov \textit{et al.}, Phys.Rev.Lett. \textbf{120}, 263203 (2018).