The image depicts the generation of high-dimensional orbital angular momentum (OAM) comb by an azimuthal binary phase. The proposed azimuthal phase is 0-π binarized, with a series of azimuthal transition lines dividing the phase value 0 and π. Such phase element can transform a Gaussian beam into an OAM multiplexed beam consisting of multiple equally spaced OAM channels with identical power−namely, an OAM comb.
Periodic poling of resonant lithium niobate metasurfaces modifies their nonlinearity and enables tailoring the diffraction pattern of second harmonic generated by the metasurface. It adds another degree of freedom for designing nonlinear metasurfaces.
The small size and rich functions of metasurfaces have great potential for the development of new optical devices. The research group theoretically proved that the metasurface can realize the complete decoupling of the near-field and far-field functions of the same polarization at two working wavelengths. While the near-field encodes intensity patterns, the far-field functions can be holographic, focusing, and beam deflecting. The cover image shows that when a metasurface is illuminated by the light at 1064 nm and 1550 nm, the near-field intensity distribution displays the numbers 1064 and 1550, and the holographic pattern shows the emblem of Nanjing University and its landmark building North Building.
Helical laser beams, due to their unique field structure, are ideal optical drivers for producing monoenergetic, pellet-like electron bunches. In contrast to regular laser beams, their field structure close to the axis of the beam is dominated by longitudinal electric and magnetic fields. The bunches are generated as a result of two synergetic effects that take place when such a beam is reflected off a mirror: the longitudinal electric field accelerates electrons after extracting them from the mirror surface; while the magnetic field confines them into the central region, allowing for acceleration within the laser over a long duration.
The image on the cover for Advanced Photonics Volume 5 Issue 1 illustrates a torus-knot configuration of a toroidal layer in the Hopf fibration and its vectorial properties of a photonic hopfion, which is controllably transported in free space. The image is based on original research presented in the article by Yijie Shen, Bingshi Yu, Haijun Wu, Chunyu Li, Zhihan Zhu, and Anatoly V. Zayats, “Topological transformation and free-space transport of photonic hopfions,” Adv. Photonics 5(1), 015001 (2023), doi: 10.1117/1.AP.5.1.015001.
High-pressure gas-jet optical shaping by four nanosecond-laser pulse generated blast waves. The computational study reveals that magnetic vortex acceleration delivers protons with maximum energies beyond 10 MeV when the ZEUS ultra-intense 45 TW, 25 fs laser pulse, interacts with the near-critical density, compressed profile, at the Institute of Plasma Physics & Lasers of the Hellenic Mediterranean University.
Flexible manipulation of Bessel beams based on Moiré metasurfaces. Both order and nondiffractive distance of the Bessel beams can be tuned by relatively rotating two metasurfaces. This device provides a new opportunity for high-capacity optical communication and high-precision nondestructive imaging.
This paper shows that by leveraging the strong angular dispersion of the metasurface, the degree of spatial entanglement quantified by the Schmidt number can be decreased or increased by changing the pump laser wavelength and a Gaussian beam size.
Researchers from École Polytechnique Fédérale de Lausanne (EPFL) proposed a deep neural network to solve the optical scattering problem and used this neural network as a surrogate forward model in the iterative reconstruction of the optical diffraction tomography. The image on the cover for Advanced Photonics Volume 4 Issue 6 provides a visual representation of this physics-informed deep neural network used for 3D optical imaging.