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Controlling the orbital angular momentum of high harmonic vortices

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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 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.

No MeSH data available.


Characterization of wavefronts and modulation of topological charges.(a) Schematic of the interferometric wavefront characterization procedure. (b,c,d) Interference patterns of the Gaussian reference beams and OAM beams of charges lXUV=+1, 0, −1. (e) The sign of topological charge at −1st order diffraction is flipped from lXUV=−1 to lXUV=+1 by changing the incident polarization.
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f3: Characterization of wavefronts and modulation of topological charges.(a) Schematic of the interferometric wavefront characterization procedure. (b,c,d) Interference patterns of the Gaussian reference beams and OAM beams of charges lXUV=+1, 0, −1. (e) The sign of topological charge at −1st order diffraction is flipped from lXUV=−1 to lXUV=+1 by changing the incident polarization.

Mentions: We use interferometry to characterize the wavefront and the direction of the helices. The experimental set-up for measuring the phase structure is shown in Fig. 3a. A third coherent infrared driving beam is now added to the experiment to produce a reference XUV beam. After passing through the spectrograph, the harmonics from the two sources interfere on the microchannel plate. Figure 3b–d shows the interference patterns between the reference XUV beams and diffracted XUV vortex beams. For the +1st order diffracted beam, the forked pattern has one more fringe on the left than on the right, labelled by dashed line in Fig. 3b. In contrast, the interference of the reference beam with the −1st order (Fig. 3d) shows one additional fringe on the right. This difference in the fringe pattern indicates the opposite handedness of the helical wavefronts.


Controlling the orbital angular momentum of high harmonic vortices
Characterization of wavefronts and modulation of topological charges.(a) Schematic of the interferometric wavefront characterization procedure. (b,c,d) Interference patterns of the Gaussian reference beams and OAM beams of charges lXUV=+1, 0, −1. (e) The sign of topological charge at −1st order diffraction is flipped from lXUV=−1 to lXUV=+1 by changing the incident polarization.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5382317&req=5

f3: Characterization of wavefronts and modulation of topological charges.(a) Schematic of the interferometric wavefront characterization procedure. (b,c,d) Interference patterns of the Gaussian reference beams and OAM beams of charges lXUV=+1, 0, −1. (e) The sign of topological charge at −1st order diffraction is flipped from lXUV=−1 to lXUV=+1 by changing the incident polarization.
Mentions: We use interferometry to characterize the wavefront and the direction of the helices. The experimental set-up for measuring the phase structure is shown in Fig. 3a. A third coherent infrared driving beam is now added to the experiment to produce a reference XUV beam. After passing through the spectrograph, the harmonics from the two sources interfere on the microchannel plate. Figure 3b–d shows the interference patterns between the reference XUV beams and diffracted XUV vortex beams. For the +1st order diffracted beam, the forked pattern has one more fringe on the left than on the right, labelled by dashed line in Fig. 3b. In contrast, the interference of the reference beam with the −1st order (Fig. 3d) shows one additional fringe on the right. This difference in the fringe pattern indicates the opposite handedness of the helical wavefronts.

View Article: PubMed Central - PubMed

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 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.

No MeSH data available.