ИСТИНА

We study the control of the ellipticity of high harmonics generated in gas, driven by a two-colour laser field. Our pioneer work demonstrated the possibility to generate elliptically-polarized harmonics using linearly polarized driving fields [1]. Exploiting a Mach-Zehnder configuration, we go here a step further, mainly by changing the crossing angle of the driving fields’ linear polariza-tions. For values higher than 45°, a significant ellipticity (around 50%) is obtained for both odd and even harmonics. Furthermore, we show the possibility to modify the polarization axis of the individual harmonics. These measurements allow envisaging a full polarization control of harmonics and a better understanding of the generation process.