Figure 1: Scheme to generate EUV high-order harmonics from conical refraction (CR) beams: an intense NIR CR beam generated with a biaxial crystal is focused onto a gas jet.
From: Extreme Ultraviolet Fractional Orbital Angular Momentum Beams from High Harmonic Generation
The left inset shows the NIR CR beam intensity distribution at the focal plane. The linear polarization distribution (depicted with white arrows) rotates along the azimuth. High-order harmonics are generated in each atom of the gas jet, and then propagated towards a far-field detector. The right inset shows the far-field HHG intensity and polarization distributions, which retain the CR-like beam structure.
