scholarly journals Capacity of a Radio Vortex Communication System Using a Partial Angular Aperture Receiving Scheme under the Horizontal Non-Kolmogorov Model

Sensors ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 1778
Author(s):  
Qian Ma ◽  
Hengkai Zhao
Keyword(s):  
Angular Momentum ◽  
Atmospheric Turbulence ◽  
Orbital Angular Momentum ◽  
Communication System ◽  
Propagation Distance ◽  
Vortex Beam ◽  
Frequency Range ◽  
Long Distance ◽  
Angular Aperture ◽  
Transmission Frequency

A partial receiving scheme based on limited angular aperture multi-beam receiving and demultiplexing can solve the difficulty caused by the divergence of the vortex beam in the conventional whole beam receiving scheme and realize the long-distance transmission of the vortex wave. The propagation of the radio vortex beam in atmospheric turbulence is of significant importance in theoretical study and practical applications. In this paper, the influence of atmospheric turbulence on the performance of a radio vortex (RV) communication system based on a partial angular aperture receiving (PAAR) scheme under the horizontal non-Kolmogorov channel model is studied. The spiral spectrum of the PAAR scheme and the channel capacity of the RV communication system using the PAAR scheme are derived. Simulation results demonstrate that the selected transmission frequency range has a great influence on the RV communication system based on the PAAR scheme, and the choice of the orbital angular momentum (OAM) mode number L has an influence on the propagation distance. The capacity of RV communication systems based on the PAAR scheme increases with the increase of the transmission frequency in the selected transmission frequency range of 10 GHz–60 GHz. When the number of orbital angular momentum (OAM) modes L is small, we can improve the signal-to-noise ratio (SNR) to obtain a larger capacity of the RV communication system based on the PAAR scheme over a longer propagation distance.

scholarly journals Generating Different Polarized Multiple Vortex Beams at Different Frequencies from Laminated Meta-Surface Lenses

Micromachines ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 61
Author(s):  
Pengfei Gao ◽  
Rui Yang
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Communication System ◽  
The Other ◽  
Vortex Beam ◽  
Other Hand ◽  
High Efficient ◽  
Linearly Polarized ◽  
Vortex Beams ◽  
The Way

We demonstrate the generation of multiple orbital angular momentum (OAM) vortex beams with different radiating states at different frequencies through a laminated meta-surface lens consisting of a dual polarized meta-array interconnected with a frequency selective meta-array. The co-linearly polarized (LP) waves from the source can directly penetrate the meta-surface lens to form multiple OAM vortex beams at one frequency. On the other hand, the meta-surface lens will be capable of releasing the cross-LP counterparts at another frequency with high-efficient polarization conversions to have multiple OAM vortex radiations with different radiating directions and vortex modes. Our design, using laminated meta-surface lens to synthesize multiple OAM vortex beams with orthogonal polarizations at different frequencies, should pave the way for building up more advanced vortex beam communication system with expanded diversity of the meta-device.

Propagation of optical orbital-angular-momentum quantum resources via maritime atmospheric turbulence

2019 ◽  
Vol 33 (16) ◽  
pp. 1950162
Author(s):  
Mei-Song Wei ◽  
Yun Zhu ◽  
Jicheng Wang ◽  
Yixin Zhang ◽  
Zheng-Da Hu
Keyword(s):  
Angular Momentum ◽  
Light Source ◽  
Atmospheric Turbulence ◽  
Orbital Angular Momentum ◽  
Propagation Distance ◽  
Angular Momenta ◽  
Quantum Numbers ◽  
The One

We study the propagations of quantum resources encoded in orbital angular momenta of two photons via the turbulent maritime atmosphere. The decay characteristics of entanglement, discord and coherence are studied for the cases of increasing propagation distance, different azimuthal quantum numbers, inner scales of turbulence and wavelengths of light source. We find that the entanglement does not suffer sudden vanishing for the one-side turbulent channels case while entanglement disappears nonasymptotically for a general case of two-side different turbulent channels similar to the specific case of two-side identical turbulent channels. Entanglement, discord and coherence have quite different decay laws and coherence possesses more robustness against the turbulence than entanglement and discord. Our results show that larger azimuthal quantum numbers and larger wavelength of light source may boost the quality of distributions of quantum resources in turbulent maritime atmosphere.

scholarly journals Anomalous Bessel vortex beam: modulating orbital angular momentum with propagation

Nanophotonics ◽  
2018 ◽  
Vol 7 (3) ◽  
pp. 677-682 ◽  
Author(s):  
Yuanjie Yang ◽  
Xinlei Zhu ◽  
Jun Zeng ◽  
Xingyuan Lu ◽  
Chengliang Zhao ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Quantum Information ◽  
Orbital Angular Momentum ◽  
Topological Charge ◽  
Propagation Distance ◽  
Zero Order ◽  
Vortex Beam ◽  
Bessel Beams ◽  
Propagation Axis ◽  
Continuous Range

AbstractZero-order and higher-order Bessel beams are well-known nondiffracting beams. Namely, they propagate with invariant profile (intensity) and carry a fixed orbital angular momentum. Here, we propose and experimentally study an anomalous Bessel vortex beam. Unlike the traditional Bessel beams, the anomalous Bessel vortex beam carries decreasing orbital angular momentum along the propagation axis in free space. In other words, the local topological charge is inversely proportional to the propagation distance. Both the intensity and phase patterns of the generated beams are measured experimentally, and the experimental results agree well with the simulations. We demonstrate an easy way to modulate the beam’s topological charge to be an arbitrary value, both integer and fractional, within a continuous range. The simplicity of this geometry encourages its applications in optical trapping and quantum information, and the like.

scholarly journals Modal coupling and crosstalk due to turbulence and divergence on free space THz links using multiple orbital angular momentum beams

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Zhe Zhao ◽  
Runzhou Zhang ◽  
Hao Song ◽  
Kai Pang ◽  
Ahmed Almaiman ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Atmospheric Turbulence ◽  
Channel Capacity ◽  
Orbital Angular Momentum ◽  
Beam Waist ◽  
Modal Coupling ◽  
Divergence Effect ◽  
Power Leakage ◽  
Calm Weather ◽  
Bad Weather

AbstractOrbital-angular-momentum (OAM) multiplexing has been utilized to increase the channel capacity in both millimeter-wave and optical domains. Terahertz (THz) wireless communication is attracting increasing attention due to its broadband spectral resources. Thus, it might be valuable to explore the system performance of THz OAM links to further increase the channel capacity. In this paper, we study through simulations the fundamental system-degrading effects when using multiple OAM beams in THz communications links under atmospheric turbulence. We simulate and analyze the effects of divergence, turbulence, limited-size aperture, and misalignment on the signal power and crosstalk of THz OAM links. We find through simulations that the system-degrading effects are different in two scenarios with atmosphere turbulence: (a) when we consider the same strength of phasefront distortion, faster divergence (i.e., lower frequency; smaller beam waist) leads to higher power leakage from the transmitted mode to neighbouring modes; and (b) however, when we consider the same atmospheric turbulence, the divergence effect tends to affect the power leakage much less, and the power leakage increases as the frequency, beam waist, or OAM order increases. Simulation results show that: (i) the crosstalk to the neighbouring mode remains < − 15 dB for a 1-km link under calm weather, when we transmit OAM + 4 at 0.5 THz with a beam waist of 1 m; (ii) for the 3-OAM-multiplexed THz links, the signal-to-interference ratio (SIR) increases by ~ 5–7 dB if the mode spacing increases by 1, and SIR decreases with the multiplexed mode number; and (iii) limited aperture size and misalignment lead to power leakage to other modes under calm weather, while it tends to be unobtrusive under bad weather.

On-chip discrimination of orbital angular momentum of light with plasmonic nanoslits

Nanoscale ◽  
2016 ◽  
Vol 8 (4) ◽  
pp. 2227-2233 ◽  
Author(s):  
Shengtao Mei ◽  
Kun Huang ◽  
Hong Liu ◽  
Fei Qin ◽  
Muhammad Q. Mehmood ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Optical Communication ◽  
Communication System ◽  
Degree Of Freedom ◽  
System Capacity ◽  
Optical Communication System ◽  
On Chip

The orbital angular momentum (OAM) of light can be taken as an independent and orthogonal degree of freedom for multiplexing in an optical communication system, potentially improving the system capacity to hundreds of Tbits per second.

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