Enhancing Performance of Air–Ground OAM Communication System Utilizing Vector Vortex Beams in the Atmosphere

Abstract

The modified uplink and downlink atmospheric turbulence channel models were established and employed to assess the system performance of air–ground orbital angular momentum (OAM) communication. The advantage of the vector vortex beam taking the place of the scalar one in the OAM communication system operated in the atmospheric turbulence was verified, that vector vortex beam can guarantee the more homogeneous energy in the circular hollow beam profile and the less phase distortion on signal OAM in the turbulence, which can reduce OAM crosstalk and improve OAM communication performance, especially small topological charge in strong turbulent regime. With the increase in turbulence strength, the vortex beam with a larger topological charge suffered more OAM mode crosstalk, and the average BER of the OAM communication system increased. Bessel–Gaussian (BG) beams with larger beam shape parameters had the strong capability of turbulence disturbance rejection in short-distance atmospheric applications, conversely, Laguerre–Gaussian (LG) beams with suitable parameter selection were preferred for long-distance atmospheric applications. Additionally, compared to the downlink channel, the transmission of OAM mode and the related communication system in the uplink channel are dramatically deteriorated due to atmospheric turbulent effects.

Performance of Orbital Angular Momentum Communication for a Non-Uniformly Correlated High-Order Bessel–Gaussian Beam in a Turbulent Atmosphere

“…where I(z) describes the intensity of the signal OAM beam, and the term ∑ ∞ ∆l=−∞ I(z) denotes the intensity of both the signal OAM beam and the crosstalk OAM beams. To describe the channel loss and crosstalk of the OAM communication system, a signal-tonoise ratio (SNR) per bit of the OAM mode for a non-uniformly correlated high-order Bessel-Gaussian beam was introduced; it is shown below [18]:…”

“…The initial OAM state will be degraded by atmospheric turbulence, followed by the OAM mode's crosstalk generation for the power of it spreading to the neighboring OAM states [6][7][8][9][10][11]. Therefore, the phase of the vortex beams is perturbed by atmospheric turbulence, the detection probability of the signal OAM state decreases [12], the signal-to-noise ratio (SNR) decreases, [13] and the bit error rate (BER) [14][15][16][17][18] increases. These are important parameters for evaluating the performance of FSO communication systems.…”

Resonance of vector vortex beams in a triangular optical cavity

“…To this kind of light beams was given the name Vector Vortex Beams (VVB) 13 . More than being a very curious type of structured light, it has been shown that they exhibit nonseparability for polarization and spatial modes 14 – 19 and there are several practical applications for them 20 – 28 .…”

Resonance of Vector Vortex Beams in a Triangular Optical Cavity

“…To this kind of light beams was given the name Vector Vortex Beams (VVB) 9 . More than being a very curious type of structured light, it has been shown that they exhibit nonseparability for polarization and spatial modes [10][11][12][13][14][15] and there are several practical applications for them [16][17][18][19][20][21][22][23][24] .…”