Exploiting Skyrmions in Free-Space Optical Communication

Abstract

In this paper, we propose a novel free-space optical (FSO) communication system utilizing optical skyrmions. We introduce a scheme referred to as skyrmion number modulation (SkM), which employs index modulation by encoding information onto the skyrmion number, a topological invariant preserved during free-space propagation. This topological nature offers the potential for inherent robustness against atmospheric turbulence-induced wavefront distortions, which limit the performance of conventional FSO systems. More specifically, we demonstrate that the fluctuation of the received skyrmion number is mitigated by a proposed intensity-based masking technique. Finally, our performance analysis based on a discrete memoryless channel framework confirms that the proposed system exhibits near-ideal robustness under weak turbulence and supports high-order modulation in moderate regimes.

Figures (3)

• Figure 1: Vector field configurations of skyrmion beams. (a) Néel-type skyrmion with $N_{\mathrm{sk}} = 1$. (b) Higher-order skyrmion with $N_{\mathrm{sk}} = 2$. (c) Anti-skyrmion with $N_{\mathrm{sk}} = -1$. (d) Néel-type skyrmion with opposite polarity, yielding $N_{\mathrm{sk}} = -1$.
• Figure 2: Schematic of beam propagation simulation using SSFM.
• Figure 3: Box plots of the estimated skyrmion numbers $\tilde{N}$ for the single positive skyrmion number transmission $N_{\mathrm{sk}} =1$, $4$, and $8$: (a) weak ($C_n^2=1.0\times10^{-15}$), (b) moderate ($C_n^2=2.5\times10^{-14}$), and (c) strong turbulence ($C_n^2 = 1.0 \times 10^{-13}$). Red line represents the transmitted $N_{\mathrm{sk}}$ values.