Adaptive free-space optical communications through turbulence using self-healing Bessel beams

Abstract

We present a scheme to realize obstruction- and turbulence-tolerant free-space orbital angular momentum (OAM) multiplexing link by using self-healing Bessel beams accompanied by adaptive compensation techniques. Compensation of multiple 16-ary quadrature amplitude modulation (16-QAM) data carrying Bessel beams through emulated atmospheric turbulence and obstructions is demonstrated. The obtained experimental results indicate that the compensation scheme can effectively reduce the inter-channel crosstalk, improve the bit-error rate (BER) performance, and recuperate the nondiffracting property of Bessel beams. The proposed scheme might be used in future high-capacity OAM links which are affected by atmospheric turbulence and obstructions.

Free-space creation of ultralong anti-diffracting beam with multiple energy oscillations adjusted using optical pen

“…However, it was not until 1987 that the advent of Bessel beam brings the hope of addressing successfully this issue 1 , and great success has been achieved in the study of anti-diffracting light beams since then 1 – 13 . Every breakthrough regarding these light beams leads to the development of many applications, including optical imaging 14 – 16 , optical trapping 17 – 19 , optical communication 20 – 22 , and laser-assisted guiding of electric discharges 23 . All advances are associated with the long anti-diffracting distances of these light beams.…”

Spin-Orbit Angular Momentum Conversion in Metamaterials and Metasurfaces

“…Traditional methods for generation of OAM beam include spatial light modulators (SLM), holograms, laser-mode conversion and spiral phase plates (SPP) (Figure 1). On the other hand, metasurfaces can create helical wave fronts by arranging nanoantennas with linearly increasing (or decreasing) phase shifts along the azimuthal direction [59,60,61,62,63,64,65,25]. As a result, a metasurface can add an optical vortex to the incident light wave front, thus converting SAM into OAM, this transformation is also termed spin-to-orbit conversion (SOC) [66,67,44,42,43].…”

Orbital Angular Momentum Multiplexed Free-Space Optical Communication Systems Based on Coded Modulation

“…There are several ways to mitigate the inter-mode crosstalk, including wavefront sensor (WFS) or wavefront sensorless based adaptive optics (AO) systems [21][22][23], digital multi-input multi-output (MIMO) equalization [24][25][26], and advanced forward error correction (FEC) based channel coding techniques [27][28][29]. AO systems are usually implemented in satellite communications to mitigate wavefront distortion, while their commercial application in near-Earth FSO links is greatly limited by the expensive WFS and deformable mirror (DM).…”