Controlling the orbital angular momentum of high harmonic vortices

Abstract

Optical vortices, which carry orbital angular momentum (OAM), can be flexibly produced and measured with infrared and visible light. Their application is an important research topic for super-resolution imaging, optical communications and quantum optics. However, only a few methods can produce OAM beams in the extreme ultraviolet (XUV) or X-ray, and 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. Such a light source is also ideal for space communications, both in the classical and quantum regimes.

Orbital-angular-momentum mixing in type-II second-harmonic generation

“…It has already been investigated in frequency up [38][39][40][41][42][43][44][45][46], and down [47][48][49] conversion, optical parametric oscillation [50][51][52][53], four-wave mixing in atomic vapors [54,55] and high harmonic generation [56,57]. The control of the nonlinear optical interaction through polarization has been also considered both in the quantum [3] and classical regimes [41,58].…”

Generation and Applications of Extreme-Ultraviolet Vortices

“…In the non-collinear geometry, the generated harmonic beams carrying various OAM are distributed spatially with an angle related to their topological charge, while there are spatially overlapped in the collinear geometry. Notice that the same experiment has been also performed with two beams of the same wavelength [23]. These beam-mixing configurations make HHG a feasible tool to produce femtosecond XUV/X-ray pulses carrying a controllable amount of OAM.…”

“…[19] by measuring the transverse phase by an interferometric technique. Very recently, different approaches that make use of specific driving laser configurations have been proposed to control and tune the OAM content of the harmonic vortices [20][21][22][23], as we will describe below. Two theoretical approaches were described in Refs.…”

Overcoming the efficiency-bandwidth tradeoff for optical harmonics generation using nonlinear time-variant resonators

“…High harmonic generation (HHG) from structured surfaces [7,8,[32][33][34] leads to a variety of exciting applica-tions, including all-optical probing of the electronic band structure [35] and the generation of high angular momentum UV beams [36,37] for high-resolution lithography [38] and imaging [39]. Moreover, the utilization of mid-infrared (sub-bandgap) laser pulses can enable efficient HHG from solids through processes similar to those in gases in the strong field ionization (SFI) regime [40][41][42][43].…”