1-Pbps orbital angular momentum fibre-optic transmission.

Area of Science:

• Optics and Photonics
• Telecommunications Engineering

Background:

• Space-division multiplexing (SDM) is crucial for future ultra-high capacity fiber-optic communications.
• Scalability challenges arise from computation-intensive multi-input multi-output (MIMO) digital signal processing (DSP) needed to manage crosstalk in SDM systems.

Purpose of the Study:

• To demonstrate a novel SDM system leveraging orbital angular momentum (OAM) modes in ring core fibers (RCFs).
• To achieve ultra-high capacity transmission with significantly reduced MIMO DSP complexity.

Main Methods:

• A 34 km, 7-core RCF system combined SDM with C+L band dense wavelength-division multiplexing (DWDM).
• Exploited unique OAM mode propagation characteristics within RCFs to minimize inter-modal and inter-core crosstalk.
• Employed fixed-size 4x4 MIMO DSP modules with a low tap count (≤25).

Main Results:

• Achieved a total raw capacity of 1.223 Peta-bit per second (Pbps) and a net capacity of 1.02 Pbps.
• Demonstrated ultra-low MIMO complexity (4x4, ≤25 taps) for a capacity exceeding 1 Pbps.
• Attained a spectral efficiency of 156.8 (130.7) bit/s/Hz (raw/net) with a small fiber cladding diameter.

Conclusions:

• The study successfully surpassed the 1 Pbps milestone for OAM-based fiber-optic communication links.
• The demonstrated system offers ultra-low MIMO complexity and modular expandability, paving the way for future capacity scaling.
• This work represents a significant advancement in SDM transmission, highlighting the potential of OAM modes in RCFs.