ИСТИНА

Light sources based on the generation of laser high-order harmonics in gas (HHG) are complementary to free-electron lasers (FEL’s). Indeed, they can be used to trigger the FEL emission (either in coherent-harmonic or in direct-seeding configurations) or, in combination with the latter, to perform VUV/X-Ray pump-probe experiments. When produced in standard (single-colour) mode, the properties of HHG pulses are quite well known. However, the same is not true when the process is driven by two pulses with different wavelengths. In this work, we studied the properties of the HHG emission as a function of the intensity, the delay and the reciprocal polarization of the generating (!+2!, with !=800 nm) pulses. For this purpose, we implemented a Mach-Zehnder interferometer on the HHG facility in operation at the Laboratoire d’Optique Appliquée of Palaiseau. Our study demonstrates the possibility to produce harmonic radiation with tunable (linear and circular) polarization.