10 Spatial mode transmission using low differential mode delay 6-LP fiber using all-fiber photonic lanterns.

Area of Science:

• Optical Communications
• Photonics
• Fiber Optics

Background:

• Space division multiplexing (SDM) transmission systems require higher spatial multiplicity for cost benefits.
• Increasing spatial channels in few-mode fibers is crucial for longer transmission distances and reduced computational complexity.
• Low differential mode group delay (DMGD) is essential for effective multi-mode fiber transmission.

Purpose of the Study:

• To investigate a method for increasing spatial mode channels within a single-core few-mode fiber.
• To demonstrate wavelength and mode-division multiplexed transmission over a low-DMGD fiber.
• To showcase a novel receiver architecture for multi-mode transmission.

Main Methods:

• Fabrication of a low-DMGD 6-LP-mode fiber.
• Utilized low-loss all-fiber 10-port photonic lanterns for light coupling.
• Implemented a time-domain SDM receiver with 20x20 MIMO digital signal processing.
• Employed a novel round-robin encoding technique.

Main Results:

• Achieved wavelength and mode-division multiplexed transmission over 4.45 km of low-DMGD fiber.
• Measured a minimum DMGD of 0.2 ns (maximum 0.357 ns) after 4.45 km.
• Successfully captured 10 spatial mode channels (over both polarizations) using only 3 coherent receivers.
• Demonstrated a 10x increase in single-core multi-mode transmission capacity.

Conclusions:

• The study presents a viable route to increasing spatial channels in few-mode fibers.
• The developed time-domain SDM receiver significantly reduces hardware complexity.
• The novel encoding technique ensures stable performance, proving the feasibility of enhanced single-core transmission capacity.