scholarly journals An Orbital Angular Momentum (OAM) Mode Reconfigurable Antenna for Channel Capacity Improvement and Digital Data Encoding

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Baiyang Liu ◽  
Guoying Lin ◽  
Yuehui Cui ◽  
RongLin Li
Keyword(s):  
Angular Momentum ◽  
Channel Capacity ◽  
Orbital Angular Momentum ◽  
Digital Data ◽  
Reconfigurable Antenna ◽  
Data Encoding ◽  
Capacity Improvement

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.

Experimental demonstration of 20  Gbit/s data encoding and 2  ns channel hopping using orbital angular momentum modes

2015 ◽  
Vol 40 (24) ◽  
pp. 5810 ◽  
Author(s):  
Asher J. Willner ◽  
Yongxiong Ren ◽  
Guodong Xie ◽  
Zhe Zhao ◽  
Yinwen Cao ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Experimental Demonstration ◽  
Data Encoding ◽  
Channel Hopping

The analysis of high-capacity quantum secure direct communication using polarization and orbital angular momentum of photons

2019 ◽  
Vol 34 (02) ◽  
pp. 2050017 ◽  
Author(s):  
Lin-Yi Li ◽  
Tie-Jun Wang ◽  
Chuan Wang
Keyword(s):  
Angular Momentum ◽  
Quantum Information ◽  
Channel Capacity ◽  
Orbital Angular Momentum ◽  
Quantum Communication ◽  
High Capacity ◽  
Quantum Secure Direct Communication ◽  
Noise Elimination ◽  
Long Distance ◽  
Direct Communication

Higher channel capacity and noise elimination are the key requirements for the implementation of long-distance quantum communication. As the additional degrees of freedom (DoF) of photons can be employed to achieve higher channel capacity and security beyond the polarizations DoF of photons, the photonic qubits are always employed as the flying qubits in quantum communication and quantum information processing. Here, exploiting the multiple DoFs of photons, we present an efficient quantum secure direct communication protocol based on the coding and manipulation of qubits on both the polarization and the orbital angular momentum of photons. Also, the numerical simulation is studied to further clarify the improvement of the channel capacity and the security. It is found that the channel capacity and the error rate (caused by eavesdropping) of the QSDC protocol which encoded on the polarization DoF and the OAM DoF is significantly higher than that of coding on only polarization DoF. We believe this work could provide more evidence for the applications of higher-dimensional qubits in quantum information science.

scholarly journals Single-End Adaptive Optics Compensation for Emulated Turbulence in a Bi-Directional 10-Mbit/s per Channel Free-Space Quantum Communication Link Using Orbital-Angular-Momentum Encoding

Research ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Cong Liu ◽  
Kai Pang ◽  
Zhe Zhao ◽  
Peicheng Liao ◽  
Runzhou Zhang ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Adaptive Optics ◽  
Orbital Angular Momentum ◽  
Quantum Communication ◽  
Forward Direction ◽  
Symbol Error Rate ◽  
Communication Link ◽  
Data Encoding ◽  
Wavefront Distortion ◽  
Turbulence Effects

A single-end adaptive-optics (AO) module is experimentally demonstrated to mitigate the emulated atmospheric turbulence effects in a bi-directional quantum communication link, which employs orbital angular momentum (OAM) for data encoding. A classical Gaussian beam is used as a probe to detect the turbulence-induced wavefront distortion in the forward direction of the link. Based on the detected wavefront distortion, an AO system located on one end of the link is used to simultaneously compensate for the forward and backward channels. Specifically, with emulated turbulence and when the probe is turned on, the mode purity of photons carrying OAM l=1 is improved by ~ 21 % with AO mitigation. We also measured the performance when encoding data using OAM {l=-1,+2} and {l=-2,+1} in the forward and backward channels, respectively, at 10 Mbit/s per channel with one photon per pulse on average. For this case, we found that the AO system could reduce the turbulence effects increased quantum-symbol-error-rate (QSER) by ~ 76 % and ~ 74 %, for both channels in the uni-directional and bi-directional cases, respectively. Similar QSER improvement is observed for the opposite direction channels in the bi-directional case.

scholarly journals Single-End Adaptive Optics Compensation for Emulated Turbulence in a Bi-Directional 10-Mbit/s per Channel Free-Space Quantum Communication Link Using Orbital-Angular-Momentum Encoding

Research ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Cong Liu ◽  
Kai Pang ◽  
Zhe Zhao ◽  
Peicheng Liao ◽  
Runzhou Zhang ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Adaptive Optics ◽  
Orbital Angular Momentum ◽  
Quantum Communication ◽  
Forward Direction ◽  
Symbol Error Rate ◽  
Communication Link ◽  
Data Encoding ◽  
Wavefront Distortion ◽  
Turbulence Effects

A single-end adaptive-optics (AO) module is experimentally demonstrated to mitigate the emulated atmospheric turbulence effects in a bi-directional quantum communication link, which employs orbital angular momentum (OAM) for data encoding. A classical Gaussian beam is used as a probe to detect the turbulence-induced wavefront distortion in the forward direction of the link. Based on the detected wavefront distortion, an AO system located on one end of the link is used to simultaneously compensate for the forward and backward channels. Specifically, with emulated turbulence and when the probe is turned on, the mode purity of photons carrying OAM l=1 is improved by ~ 21 % with AO mitigation. We also measured the performance when encoding data using OAM {l=-1,+2} and {l=-2,+1} in the forward and backward channels, respectively, at 10 Mbit/s per channel with one photon per pulse on average. For this case, we found that the AO system could reduce the turbulence effects increased quantum-symbol-error-rate (QSER) by ~ 76 % and ~ 74 %, for both channels in the uni-directional and bi-directional cases, respectively. Similar QSER improvement is observed for the opposite direction channels in the bi-directional case.

scholarly journals On the Orbital Angular Momentum Incident Fields in Linearized Microwave Imaging

Sensors ◽  
2020 ◽  
Vol 20 (7) ◽  
pp. 1905
Author(s):  
Santi Concetto Pavone ◽  
Gino Sorbello ◽  
Loreto Di Donato
Keyword(s):  
Angular Momentum ◽  
Wireless Communications ◽  
Channel Capacity ◽  
Orbital Angular Momentum ◽  
Microwave Imaging ◽  
Next Generation ◽  
First Order ◽  
Rytov Approximation

Orbital angular momentum (OAM) is gaining great attention in the physics and electromagnetic community owing to an intriguing debate concerning its suitability for widening channel capacity in next-generation wireless communications. While such a debate is still a matter of controversy, we exploit OAM generation for microwave imaging within the classical first order linearized models, i.e., Born and Rytov approximation. Physical insights into different fields carrying ℓ-order OAM are conveniently exploited to propose possible alternative imaging approaches and paradigms in microwave imaging.

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