Orbital Angular Momentum Neural Communications for 1-to-40 Multicasting with 16-Ary Shift Keying

Abstract

Orbital angular momentum (OAM) can be employed as information carrier in optical communications, which include OAM multicasting where separate OAM beams are produced to construct one-to-many links, and OAM shift keying where different OAM states are used for symbol coding. However, it remains a significant challenge to achieve a hyperscale OAM multicasting with OAM shift keying simultaneously, due to the deviation of complex OAM spectral components at the transmitter. Here, we demonstrate the concept of OAM neural communication by developing a high-precision, noniterative and ultra-multi-user optical communication coding scheme based on a deep-learning U-net neural network. The neural network is trained with only small datasets (there are 10 10 datasets in total, but only 10 3 datasets are used) to predict the OAM spectrum of ultra-high precision, with the mean square error (MSE) evaluated as 0.02 in all OAM channels. As a proof of concept, we experimentally demonstrate 1-to-40 multicasting with 16-ary shift keying in OAM communication. After a 3-meter free space transmission, we realize the encoding and decoding of 40 images with 16 gray values with a BER of 0. Moreover, our artificial intelligence-based methodology can be extended to manipulate three-dimensional OAM pixel arrays for holographic display and optical trapping.

Research Progress on Router Devices for the OAM Optical Communication

“…Multicasting Extended communication link [95][96][97][98][99][100][101][102][103][104][105][106][107][108][109][110][111][112] Switching Exchanging data [113][114][115][116][117][118][119][120][121][122][123][124][125][126][127] Filtering Extracting specific channel [128][129][130][131][132][133][134][135][136][137][138][139][140] Hopping Anti-interference [141][142][143][144]…”

“…First, the Gaussian beam emitted from the collimator is transformed into an OAM beam using a spatial light modulator (SLM) loaded with a helical phase distribution to generate a single OAM channel. And then, the input single Extended communication link [95][96][97][98][99][100][101][102][103][104][105][106][107][108][109][110][111][112] Switching…”

“…The results demonstrate that the system can significantly improve the signal quality, reducing the error vector amplitude (EVM) from 25.4% to 12.9% in the presence of 336 ps/nm chromatic dispersion, as depicted in Table 2. The mean square error is 0.02, BER of 0 [109] In order to further increase the channel utilization rate, in 2022, Shang et al [108] proposed a multiplexed vortex state array consisting of multiple multiplexed vortex beams, which allows for flexible manipulation of both the spatial position and the corresponding OAM spectrum as desired (Figure 1c1). Then, employing an array as a data-carrier, the research group demonstrated a one-to-many multicasting link through multi-state OAM shift keying, where four various states were utilized to encode a four-bit symbol, achieving high-dimensional encoding; the experimental setup is shown in Figure 1c2.…”

“…Therefore, a tradeoff is made between the bit error rate (BER) and the number of multiplexed channels. To address the above problem, in 2023, Meng et al [109] reported a unique concept of OAM neural communication employing a network model based on a U-net neural network (Figure 2a) to transform the complex amplitude transmission functions into phase-only holograms (Figure 2b) [109]. The phase-only hologram predicted by their proposed network model generated a high-precision OAM spectrum for OAM multicasting with OAM-SK using only a few training datasets.…”

Nanoprinted Diffractive Layer Integrated Vertical-Cavity Surface-Emitting Vortex Lasers with Scalable Topological Charge

“…l takes an infinite value in principle, and the vortex light fields with different l values are orthogonal to each other. , This unique infinitely orthogonal property makes the vortex beam a well-recognized way to greatly increase the information capacity. In the past decade, OAM-based multiplexing optical communication, − holography, − optical data storage, , optical encryption, , and quantum information have been widely investigated.…”