Equalizer tap length requirement for mode group delay-compensated fiber link with weakly random mode coupling

Area of Science:

• Optical Communications
• Fiber Optics Engineering
• Signal Processing

Background:

• Differential Modal Group Delay (DMGD) compensation is crucial for mitigating signal distortion in multi-mode fiber links.
• Weak random mode coupling presents unique challenges for equalization in these systems.
• Understanding equalizer requirements is key to optimizing high-speed optical transmission.

Purpose of the Study:

• To analytically and numerically investigate the equalizer tap length requirement for DMGD compensated fiber links.
• To determine the relationship between tap length and modal group delay under weak random mode coupling.
• To explore methods for reducing the required tap length.

Main Methods:

• Analytical investigation of equalizer tap length.
• Numerical simulations of DMGD compensated fiber links with weakly random mode coupling.
• Analysis of fiber pairs with opposite DMGD signs within each link span.

Main Results:

• The required equalizer tap length is proportional to the modal group delay of a single DMGD compensated pair, not the total link MGD.
• Under weak random mode coupling, this relationship simplifies equalization design.
• Utilizing small DMGD compensation step sizes can reduce the required tap length by two orders of magnitude.

Conclusions:

• Equalizer tap length in DMGD compensated links is primarily governed by individual compensated pairs, not the aggregate link delay.
• Effective equalization strategies can be developed by focusing on smaller compensation steps.
• This research offers a pathway to more efficient and cost-effective optical communication systems.