Mode-multiplexed transmission over conventional graded-index multimode fibers

Area of Science:

• Optical communications
• Fiber optics engineering
• Photonics

Background:

• Multimode fibers (MMFs) are cost-effective but traditionally limited in capacity.
• Mode-division multiplexing (MDM) offers a path to increase MMF capacity.
• Combining MDM with wavelength-division multiplexing (WDM) can further enhance data rates.

Purpose of the Study:

• To investigate the performance of combined mode- and wavelength-multiplexed transmission over conventional graded-index multimode fibers.
• To evaluate the feasibility of long-distance data transmission using these techniques in MMFs.
• To demonstrate the scalability of mode-division multiplexing in MMFs.

Main Methods:

• Utilized mode-selective photonic lanterns for precise mode excitation and differential group delay compensation.
• Employed spatial mode filters to suppress higher-order modes.
• Transmitted Quadrature Phase Shift Keying (QPSK) signals over multiple WDM channels, spatial modes, and polarizations.

Main Results:

• Achieved 310 km transmission using 60 WDM channels, 3 spatial modes, and 2 polarizations over a 44.3 km span.
• Reported transmission over 6 spatial modes for a 17-km single-span experiment.
• Demonstrated the potential for scalable MDM in MMFs, with possibilities for adding modes over time.

Conclusions:

• Conventional multimode fibers can support scalable mode-division multiplexing approaches.
• Long-distance mode-multiplexed transmission exceeding 300 km is achievable in standard MMFs.
• Combined mode- and wavelength-multiplexing offers a promising strategy for enhancing fiber optic communication capacity.