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Demonstration of 1 Pbps orbital angular momentum fiber optic transmission

Credit: Junyi Liu et al

Space division multiplexing (SDM) technology is showing promise in overcoming the so-called “capacity shortage” of existing single mode fiber (SMF). Now, researchers in China have experimentally demonstrated an orbital-angular-momentum (OAM)-based SDM transmission system with a total capacity greater than 1-Pb/s. The result offers significant potential for further increasing communication capacity by exploiting OAM modes in optical fibers while keeping multi-input multi-output (MIMO) processing at ultra-low complexity.

With Internet traffic approaching the capacity limit of SMF in the foreseeable future, optical communication technologies with greater transmission capacity are becoming increasingly desired. However, in the reported solutions that add more cores and/or modes per core in a fiber to increase the total capacity, there is a fundamental bottleneck in that the complexity of the MIMO processing required for the equalization of the signal can increase in square law with the number of channels (number of modes × cores) due to inter-channel crosstalk (XT).

Simply inserting multiple cores far enough apart in a fiber to ensure a low inter-core XT will enlarge the fiber diameter, and diameters over 200 microns will seriously degrade fiber manufacturing, splicing, and reliability performance. the fiber. Therefore, new solutions are needed to balance the number of spatial channels, fiber cladding diameters, and MIMO complexity.

In a new article published in Light: science and applicationsa team of researchers led by Dr. Jie Liu and Professor Siyuan Yu from State Key Laboratory of Optoelectronic Materials and Technologies, School of Electronics and Information Technology, Sun Yat-Sen University, China, proposed and demonstrated a fiber optic transmission system based on OAM modes.

The system integrates SDM, polarization division multiplexing (PDM) and dense wavelength division multiplexing (DWDM) in the C+L band over a 34 km 7-core ring core fiber (RCF) long and 180 μm in diameter, allowing a gross (net) capacity of 1.223 (1.02) Pb/s and a spectral efficiency of 156.8 (130.7) bit/s/Hz. In this system, they used three groups of non-degenerate OAM (MG) modes per core, each MG containing 4 quasi-degenerate OAM modes (12 modes in all).

Each mode is loaded with 312 wavelengths which are all modulated by 24.5 Goaud QPSK signals. By exploring the fixed OAM mode number in each MG, the low coupling between the MGs and the cores, and the relative ease of OAM mode multiplexing, the researchers obtained simultaneous low coupling between the seven fiber cores and among the three MGs. OAM in each core, so that only a 4×4 MIMO modular processing scheme is needed to equalize the coupling between the 4 quasi-degenerate modes in each MG.

The reported method demonstrates the promise of SDM fiber optic systems with high scalability in spatial channel count and transmission capacity while maintaining low and fixed MIMO equalization complexity within a reasonable fiber cladding diameter. The researchers highlight the key role of OAM modes in achieving petabit per second of transmission:

“These results move the capacity of OAM-based fiber optic communication links above the 1 Pb/s milestone for the first time.”

“They also represent both the lowest MIMO complexity and the 2n/a smallest fiber cladding diameter among reported multi-mode multi-core fiber (FM-MCF) SDM systems >1 Pb/s capacity,” they added.

“Therefore, the scheme demonstrates significant potentials for increasing fiber optic transmission capacity while maintaining ultra-low MIMO complexity, and hence low cost and low power consumption, by exploiting the characteristics exceptionally excellent OAM modes in ring-core optical fibers over distances of several tens of kilometers (e.g. the metro, or inter-data center links, etc.),” say the researchers.

World’s first successful transmission of 1 petabit per second in standard cladding diameter multi-core fiber

More information:
Junyi Liu et al, 1-Pbps orbital angular momentum optical fiber transmission, Light: science and applications (2022). DOI: 10.1038/s41377-022-00889-3

Provided by Chinese Academy of Sciences

Quote: 1 Pbps Orbital Angular Momentum Fiber Optic Transmission Demonstration (2022, Aug 26) Retrieved Aug 28, 2022 from fiber optic. html

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