Progress in integrated devices for optical vortex emission

Jiang, Ye; Cao, Yu; Feng, Xue

doi:10.1088/1361-6463/ab84a4

Cited by 5 publications

(1 citation statement)

References 69 publications

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“…It is worth noting that, for such radially polarized cylindrical vector vortex beams [53], a focus without an intensity minimum at its center can carry a finite value of OAM [54]. There have been many reports on off-chip vortex beam generation using a waveguide, and they utilize either a phase gradient metasurface or a decorated microring resonator [55][56][57]. Figure 5 shows that a third approach of off-chip emission exists, which is to use an amplitude gradient metasurface.…”

Section: Vortex Beam Generator As the Third Functional Devicementioning

confidence: 99%

Amplitude gradient-based metasurfaces for off-chip terahertz wavefront shaping

Lyu¹,

Huang²,

Yin³

et al. 2023

Photon. Res.

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Metasurfaces provide an effective technology platform for manipulating electromagnetic waves, and the existing design methods all highlight the importance of creating a gradient in the output phase across light scattering units. However, in the emerging research subfield of meta-waveguides where a metasurface is driven by guided modes, this phase gradient-oriented approach can only provide a very limited emission aperture, significantly affecting the application potential of such meta-waveguides. In this work, we propose a new design approach that exploits the difference between meta-atoms in their light scattering amplitude. By balancing this amplitude gradient in the meta-atoms against the intensity decay in the energy-feeding waveguide, a large effective aperture can be obtained. Based on this new design approach, three different wavefront shaping functionalities are numerically demonstrated here on multiple devices in the terahertz regime. They include beam expanders that radiate a plane wave, where the beam width can increase by more than 900 times as compared to the guided wave. They also include a metalens that generates a Bessel-beam focus with a width 0.59 times the wavelength, and vortex beam generators that emit light with a tunable topological charge that can reach −30. This amplitude gradient design approach could benefit a variety of off-chip light shaping applications such as remote sensing and 6G wireless communications.

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Section: Vortex Beam Generator As the Third Functional Devicementioning

confidence: 99%

Amplitude gradient-based metasurfaces for off-chip terahertz wavefront shaping

Lyu¹,

Huang²,

Yin³

et al. 2023

Photon. Res.

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Interplay between optical vortices and condensed matter

Rosen

Tamborenea²,

Kuhn³

2022

Rev. Mod. Phys.

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Plasmonically enhanced composite vortex beam generation using ultra-thin dielectric fork gratings

2022

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We experimentally demonstrate a simple method for the generation of composite vortex beams using resonant ultra-thin dielectric fork gratings (UFGs) of thicknesses an order of magnitude less than the incident wavelength. The degradation in the diffraction efficiency of these gratings at reduced dielectric thicknesses was computationally shown to be compensated for by introducing a thin continuous gold layer (Au, 30 nm) between the grating and the substrate. At the resonance wavelength, the diffraction efficiency of UFGs with Au was ∼ 4 times higher when compared to that of UFGs without Au, which was attributed to plasmon-induced transmission enhancement. UFGs were fabricated with optimized geometric parameters using electron beam lithography. These gratings showed lattice-plasmon resonance at the wavelength corresponding to the grating vector, resulting in vortex beams with a specific wavelength and polarization selectivity. Further, hybrid UFGs were designed by replacing a central concentric circular region of a UFG with another UFG of a different topological charge. These hybrid UFGs resulted in the formation of composite vortex beams, indicating that the relative spatial phase imparted to the lattice plasmon by hybrid gratings was preserved in the leaked radiation. These results can help in designing integrated, ultra-thin, low aspect ratio optical-phase-singularity structures for enhanced optical sources, detectors, and sensing applications.

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Progress in integrated devices for optical vortex emission

Cited by 5 publications

References 69 publications

Amplitude gradient-based metasurfaces for off-chip terahertz wavefront shaping

Amplitude gradient-based metasurfaces for off-chip terahertz wavefront shaping

Interplay between optical vortices and condensed matter

Plasmonically enhanced composite vortex beam generation using ultra-thin dielectric fork gratings

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