Ultrafast polarization-tunable monochromatic extreme ultraviolet source at high-repetition-rate

We report on the development of a high-order harmonic generation (HHG)-based ultrafast high-repetition-rate (250 kHz) monochromatic extreme ultraviolet (21.6 eV) source with polarization tunability, specifically designed for multi-modal dichroism in time- and angle-resolved photoemission spectroscopy. Driving HHG using an annular beam allows us to spatially separate the high-power 515 nm driving laser from the XUV beamlet while preserving the linear polarization axis angle tunability. This enables controlling the polarization state of the XUV radiation with a fixed all-reflective phase-shifter. This scheme leads to a source brightness of 5.7 x 10(12) photons s(-1) at 21.6 eV (up to 4 x 10(11) photons s(-1) on target) with ellipticities as high as 90%.

Automated summary

We report on the development of a high-repetition-rate monochromatic extreme ultraviolet source with polarization tunability, designed for multi-modal dichroism in time- and angle-resolved photoemission spectroscopy. The scheme uses an annular beam to separate the driving laser from the XUV beamlet while preserving the polarization tunability. This results in a high brightness source at 21.6 eV with ellipticities as high as 90%.