Controlling the orbital angular momentum of high harmonic vortices
Optical vortices, which carry orbital angular momentum (OAM) is an 
important research topic for super-resolution imaging, optical communications and quantum optics. Controlling the OAM on these beams remains challenging. Here we apply wave mixing to a tabletop high-harmonic source, as proposed in our previous work, and control the topological charge (OAM value) of XUV beams. Our technique enables us to produce first-order OAM beams with the smallest possible central intensity null at XUV wavelengths. This work opens a route for carrier-injected laser machining and lithography, which may reach nanometre or even angstrom resolution.
- Kong, F., Zhang, C., Bouchard, F., Li, Z., Brown, G.G., Ko, D.H., Hammond, T.J., Arissian, L., Boyd, R.W., Karimi, E. and Corkum, P.B., 2017. Controlling the orbital angular momentum of high harmonic vortices. Nature Communications, 8, p.14970.