Ultralow-power spiking neural networks for 1024-ary orbital angular momentum shift keying free-space optical communication

Abstract

The theoretical unbounded orbital angular momentum (OAM) states can be exploited as data bits in the OAM shift keying (OAM-SK) free-space optical (FSO) communications. In order to cope with the atmospheric turbulence (AT) and misalignment in practical applications, various machine learning algorithms, or neural networks (NNs), have been put forward to decode the OAM states. However, to recognize the hybrid spatial modes representing a large bit states, the massive learnable nodes, longer computation time and more training parameters are required to improve the capability of the NNs, resulting in energy efficiency burden to the hardware device. In this paper, the event-based Spiking Neural Network (SNN) is utilized to recognize the hybrid spatial modes consisting of superposed coaxial LG modes with l ranging from 0 to 9 and p=0, which is termed as Spiking OAM-recognition neural network (Spiking-ORNN). In comparison to the previous solution of running deep neural networks (DNNs) on graphics processing units (GPUs), the neuromorphic solution of running Spiking-ORNN on neuromorphic chips exhibits 4300x higher energy efficiency without obvious sacrifice of recognition accuracy (less than 0.5%). Moreover, we experimentally demonstrate a 10-meter 1024-ary OAM-SK FSO communication for the transmission of an image with a 10-bit grey level, wherein the peak signal-to-noise ratio of the received image can exceed 41.4 dB under the AT of =1e−15 m−2/3. We anticipate that our results can stimulate further researches on the utilization of the brain-like SNN chips to reduce the energy consumptions based on the artificial-intelligence-enhanced optoelectronic systems.

Enhancing recognition performance of vortex arrays through conditional generative adversarial network-based data augmentation

“…Recently, Li demonstrated a spiking neural network to achieve 1024-ary OAM shift keying communication, enabling the transmission of 10-bit gray-level images. 19 Nevertheless, the quantity of samples is often constrained by channel interruptions, posing a significant challenge in accurately identifying the modes of input images due to class imbalance and data scarcity. 20,21 In addition, with the transmission distance increases, the brightness of optical field will decrease, resulting in a data reduction under strong turbulence.…”

Achromatic CMOS-Integrated Four-Bit Orbital Angular Momentum Mode Detector at Three Wavelengths

“…The quickly increasing data transfer load requires revolutionary breakthroughs in current optoelectronic systems. , Remarkably, the ever-increasing demand for high-capacity optical devices has prompted the use of orthogonal physical dimensions of light for optical multiplexing to process information in parallel. − In recent years, orbital angular momentum (OAM), represented by a helical wavefront, exp­(i lφ ) (where l and φ denote the helical mode index and the azimuthal angle, respectively), − has emerged as a new degree of freedom of light for boosting information capacity due to its theoretically unbounded helical mode index. − The orthogonal OAM mode states can be utilized as an information carrier, creating the pioneering concepts such as high-security encryption holography, optically addressable three-dimensional (3D) display, high-capacity optical communication, − six-dimensional data storage, and high-dimensional quantum entanglement. , To further increase the number of information channels in practical applications, the synergistic multiplexing of OAM and other physical dimensions has attracted a significant amount of attention. , For example, the light beams with distinctive spin eigenstates and OAM states can be individually controlled in a high-security nested holographic encryption scheme; the 3D optical elements encoded with color and OAM information substantially increase the number of combinations for optical anticounterfeiting and photonic lock–key devices in a pairwise fashion, and the merging of the wavelength and OAM contributes to a total data capacity on the order of Pbit per second in the field of optical communications . Among these technologies, manipulating the multidimensional light fields with compact devices is critical.…”