Orbital angular momentum from semiconductor high-order harmonics

Abstract

Light beams carrying orbital angular momentum (OAM) have led to stunning applications in various fields from quantum information to microscopy. In this letter, we examine OAM from the recently discovered high-harmonic generation (HHG) in semiconductor crystals. HHG from solids could be a valuable approach for integrated high-flux short-wavelength coherent light sources. The solid state nature of the generation medium allows the possibility to tailor directly the radiation at the source of the emission and offers a substantial degree of freedom for spatial beam shaping. First, we verify the fundamental principle of the transfer and conservation of the OAM from the generation laser to the harmonics. Second, we create OAM beams by etching a spiral zone structure directly at the surface of a zinc oxide crystal. Such diffractive optics act on the generated harmonics and produces focused optical vortices with nanometer scale sizes that may have potential applications in nanoscale optical trapping and quantum manipulation.

All semiconductor enhanced high-harmonic generation from a single nanostructured cone

“…The strong electron currents from which HHG originates can be manipulated in space and time. This, in turn, allows to localize the HHG process in time at the single optical cycle scale 4 and in space at a nanometer scale to create for example beams that carry orbital angular momentum 11 . This control can not only revolutionize attosecond science but also prepare a new generation of ultrafast visible to X-ray optoelectronic devices operating at petahertz frequencies.…”

Spin-to-orbital angular momentum conversion in harmonic generation driven by intense circularly polarized laser

“…In the field of optical materials, some optical elements, such as q-plates [13][14][15][16][17][18], semiconductor microcavities [19], and elements using metasurface [20][21][22][23] can be used to realize spin-to-orbital angular momentum conversion (STOC) by flipping the spin direction [24]; however, only 2σ angular momentum can be converted from SAM to OAM with these techniques. STOC can also be induced in free space for nonparaxial light because of the spin-orbit interaction [25,26].…”

“…The SPP is an optical element with a helical surface. The thickness of the component increases smoothly with azimuthal position according to ( ) When a plane wave laser is reflected on the SPP, it can be converted into a vortex mode with the helical phase ( ) q il exp s in azimuth[18,32], where l s is the OAM parameter induced by the SPP. Now, let us use a vortex laser beam to normally irradiate a SPP plasma target.…”

Optique attoseconde et électronique pétahertz dans les semiconducteurs

“…Compactes et à très haut taux de répétition, faciles à manipuler grâce aux progrès de la nano-fabrication, structures appropriées par faisceau d'ions focalisés. La figure 4a illustre l'utilisation de zones de Fresnel avec une singularité en leur centre pour à la fois focaliser l'ordre harmonique souhaité et lui donner par exemple un moment angulaire orbital arbitraire, visible ici par la structure annulaire du profil d'intensité du faisceau au foyer [6].…”