1-Pbps orbital angular momentum fibre-optic transmission

Abstract

Space-division multiplexing (SDM), as a main candidate for future ultra-high capacity fibre-optic communications, needs to address limitations to its scalability imposed by computation-intensive multi-input multi-output (MIMO) digital signal processing (DSP) required to eliminate the crosstalk caused by optical coupling between multiplexed spatial channels. By exploiting the unique propagation characteristics of orbital angular momentum (OAM) modes in ring core fibres (RCFs), a system that combines SDM and C + L band dense wavelength-division multiplexing (DWDM) in a 34 km 7-core RCF is demonstrated to transport a total of 24960 channels with a raw (net) capacity of 1.223 (1.02) Peta-bit s−1 (Pbps) and a spectral efficiency of 156.8 (130.7) bit s−1 Hz−1. Remarkably for such a high channel count, the system only uses fixed-size 4 × 4 MIMO DSP modules with no more than 25 time-domain taps. Such ultra-low MIMO complexity is enabled by the simultaneous weak coupling among fibre cores and amongst non-degenerate OAM mode groups within each core that have a fixed number of 4 modes. These results take the capacity of OAM-based fibre-optic communications links over the 1 Pbps milestone for the first time. They also simultaneously represent the lowest MIMO complexity and the 2nd smallest fibre cladding diameter amongst reported few-mode multicore-fibre (FM-MCF) SDM systems of >1 Pbps capacity. We believe these results represent a major step forward in SDM transmission, as they manifest the significant potentials for further up-scaling the capacity per optical fibre whilst keeping MIMO processing to an ultra-low complexity level and in a modularly expandable fashion.

Broadband, Low‐Crosstalk, and Massive‐Channels OAM Modes De/Multiplexing Based on Optical Diffraction Neural Network

“…Taking the commonly used method as an example, N spiral phase plates and N−1 beam splitters (BSs) are needed to achieve N-channel OAM mode multiplexing or demultiplexing. [5,6] For larger N, this leads to cumbersome installation and serious energy loss, and the efficiency is at most 1/N. In response to the efficiency decay caused by BSs, a lossless scheme based on Mach-Zehnder interferometers (MZIs) was also proposed.…”

Efficient Dense Orbital Angular Momentum Demultiplexing Enabled by Quasi‐Wavelet Conformal Mapping

“…For instance, 100-Tbit/s information transmission rate has been achieved by multiplexing with 12 OAM modes, two polarizations, and 42 wavelengths; [17] and recently, 1-Pbit/s N-dimensional multiplexing transmission with OAM modes has been implemented both in free space and fiber with impressive performance. [18,22] While the principle of OAM-based optical communications has been rapidly developed, the corresponding performance of OAM multiplexing/ demultiplexing becomes the bottleneck of practical communication systems. Therefore, one central task to liberate full potential of OAM-based optical communications is to demultiplex the OAM modes accurately and efficiently.…”

“…Thirty years have passed since they were recognized in light waves, [ 1 ] meantime, they have undergone a fast development to serve as a useful tool in science and engineering. [ 2–23 ] The OAM is of great interest in optical communications, [ 12–23 ] because different OAM modes with different topological charges l can serve as a set of orthogonal bases for multiplexing communications, which are also perfectly stackable with well‐established wavelength‐division multiplexing (WDM) and polarization‐division multiplexing (PDM) techniques. As a result, using OAM modes can greatly enhance the channel capacity of communication systems.…”

“…For instance, 100‐Tbit/s information transmission rate has been achieved by multiplexing with 12 OAM modes, two polarizations, and 42 wavelengths; [ 17 ] and recently, 1‐Pbit/s N‐dimensional multiplexing transmission with OAM modes has been implemented both in free space and fiber with impressive performance. [ 18,22 ]…”

High Orbital Angular Momentum Lasing with Tunable Degree of Chirality in a Symmetry-Broken Microcavity

“…Namely, chiral-structured resonators [2,3], non-Hermitian systems [4][5][6], quantum Hall effect [7] and spin-orbit coupling [8] have been employed to construct vortex microlasers. Due to the infinite quantum numbers of OAM, optical vortices provide higher-dimensional quantum states serving as powerful sources for information encoding [9][10][11][12][13][14], ultrasensitive detection [15], and investigation of fundamental quantum mechanics [16][17][18].…”