On the performance stability of MCF-based SDM system affected by inter-core crosstalk fluctuation

Area of Science:

• Optical Communications
• Photonics
• Fiber Optics

Background:

• Inter-core crosstalk (IC-XT) in multi-core fiber (MCF) systems fundamentally limits the capacity of space-division multiplexing (SDM).
• Understanding IC-XT is crucial for optimizing high-capacity optical communication systems.

Purpose of the Study:

• To develop a closed-form expression for IC-XT magnitude in MCF systems.
• To explain the fluctuation mechanisms of short-term average crosstalk (STAXT) and bit error ratio (BER) for optical signals with and without an optical carrier.
• To investigate the impact of IC-XT on long-haul transmission performance.

Main Methods:

• Derivation of a closed-form expression for IC-XT magnitude.
• Experimental verification using a 7x10-Gb/s SDM system with real-time BER and outage probability measurements.
• Investigation in a recirculating 7-core fiber loop for long-haul transmission.
• Development of a frequency-domain IC-XT measurement technique.

Main Results:

• The proposed theory accurately explains the fluctuation behaviors of STAXT and BER.
• An unmodulated optical carrier substantially influences BER fluctuations.
• Removing the optical carrier reduced the BER fluctuation range by three orders of magnitude.
• Longer transmission distances narrowed the BER fluctuation range, indicating other factors become dominant.

Conclusions:

• The developed IC-XT model provides a theoretical basis for understanding signal fluctuations in MCF systems.
• The presence of an optical carrier significantly exacerbates BER fluctuations, highlighting its importance in system design.
• The study offers insights into mitigating IC-XT effects for enhanced performance in long-haul SDM transmission.