Plasmonic metasurfaces for far-and near-field orbital angular momentum manipulation

We study the effect of oblique illumination on the functioning of a plasmonic nanoantenna for chiral light. The antenna is designed to receive a structured beam of light and produce a nanosized near-field distribution that possesses nonzero orbital angular momentum. The design consists of metal (gold) microrods laid on a dielectric surface and is compatible with well-developed nanofabrication techniques. Experimental arrangements often require such an antenna to operate in a tilted geometry, where input light is incident on the antenna at an oblique angle. We analyze the limitations that the angled illumination imposes and discuss approaches to mitigate these limitations. Through our numerical simulations, we find that tilt angles require modifications to the antenna design. Our analysis can guide current and future experimental configurations to push the limits of resolution and sensitivity.

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Usability of Tilted Plasmon Antenna with Structured Light

10.20944/preprints202110.0144.v1 ◽

2021 ◽

Author(s):

Rafael Quintero-Torres ◽

Jorge Luis Domínguez-Juárez ◽

Mariia Shutova ◽

Alexei V. Sokolov

Keyword(s):

Angular Momentum ◽

Numerical Simulations ◽

Field Distribution ◽

Orbital Angular Momentum ◽

Near Field ◽

Dielectric Surface ◽

Antenna Design ◽

Oblique Angle ◽

Oblique Illumination ◽

To Receive

We study the effect of oblique illumination on the functioning of a plasmonic nanoantenna for chiral light. The antenna is designed to receive a structured beam of light and produce a nanosized near-field distribution that possesses non-zero orbital angular momentum. The design consists of metal (gold) micro-rods laid on a dielectric surface and is compatible with well-developed nanofabrication techniques. Experimental arrangements often require such an antenna to operate in a tilted geometry, where input light is incident on the antenna at an oblique angle. We analyze the limitations that the angled illumination imposes and discuss approaches to mitigate these limitations. Through our numerical simulations, we find that tilt angles larger than 30 degrees require modifications to the antenna design. Our analysis guides current and future experimental configurations to pushing the limits of resolution and sensitivity.

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Conservation of angular momentum in second harmonic generation from under-dense plasmas

Communications Physics ◽

10.1038/s42005-020-00474-3 ◽

2020 ◽

Vol 3 (1) ◽

Author(s):

Chen-Kang Huang ◽

Chaojie Zhang ◽

Zan Nie ◽

Kenneth A. Marsh ◽

Chris E. Clayton ◽

...

Keyword(s):

Angular Momentum ◽

Orbital Angular Momentum ◽

Pump Beam ◽

Second Harmonic ◽

Near Field ◽

Gaussian Beams ◽

Dense Plasmas ◽

Underdense Plasma ◽

Mechanical Objects ◽

Independent Parameters

AbstractSpin and orbital angular momentum of an optical beam are two independent parameters that exhibit distinct effects on mechanical objects. However, when laser beams with angular momentum interact with plasmas, one can observe the interplay between the spin and the orbital angular momentum. Here, by measuring the helical phase of the second harmonic 2ω radiation generated in an underdense plasma using a known spin and orbital angular momentum pump beam, we verify that the total angular momentum of photons is conserved and observe the conversion of spin to orbital angular momentum. We further determine the source of the 2ω photons by analyzing near field intensity distributions of the 2ω light. The 2ω images are consistent with these photons being generated near the largest intensity gradients of the pump beam in the plasma as predicted by the combined effect of spin and orbital angular momentum when Laguerre-Gaussian beams are used.

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