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This paper explores using Orbital Angular Momentum (OAM) controlled electromagnetic waves for enhanced ground penetrating radar (GPR) imaging and detection. A macroscopic interpretation of OAM is propagating waves with vortex-shaped wave fronts. At the photon level OAM appears as a quantum degree of freedom with integer quanta of angular momentum added to each photon. This is in addition to Spin Angular Momentum (SAM). The use of OAM in GPR has at least two potential advantages. The vortex shape may enable better discernment of cylindrical versus non-cylindrical buried objects. At the quantum level entanglement of OAM with other quantum degrees of freedom may enable enhanced imaging, such as the ghost imaging of objects that produce weak signal returns. The results include experiments that demonstrate the generation and reception of EM waves with a circular pattern of antennas operating as phased arrays to produce vortex-shaped waves at frequencies and dimensions typical of conventional GPRs.
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On-chip spin-orbit locking of quantum emitters in 2D materials for chiral emission
Light carries both spin angular momentum (SAM) and orbital angular momentum (OAM), which can be used as potential degrees of freedom for quantum information processing. Quantum emitters are ideal candidates towards on-chip control and manipulation of the full SAM–OAM state space. Here, we show coupling of a spin-polarized quantum emitter in a monolayer W S e 2 with the whispering gallery mode of a S i 3 N 4 ring resonator. The cavity mode carries a transverse SAM of σ = ± 1 in the evanescent regions, with the sign depending on the orbital power flow direction of the light. By tailoring the cavity–emitter interaction, we couple the intrinsic spin state of the quantum emitter to the SAM and propagation direction of the cavity mode, which leads to spin–orbit locking and subsequent chiral single-photon emission. Furthermore, by engineering how light is scattered from the WGM, we create a high-order Bessel beam which opens up the possibility to generate optical vortex carrying OAM states.
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- PAR ID:
- 10350754
- Date Published:
- Journal Name:
- Optica
- Volume:
- 9
- Issue:
- 8
- ISSN:
- 2334-2536
- Page Range / eLocation ID:
- 953
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1364/OPTICA.463481
