All-fiber 6-mode multiplexers based on fiber mode selective couplers

Area of Science:

• Optical Communications
• Photonics
• Fiber Optics

Background:

• Increasing demand for higher data transmission rates necessitates advanced multiplexing techniques.
• Mode division multiplexing (MDM) offers a promising solution by utilizing higher-order modes (HOMs) in few-mode fibers (FMFs).
• Efficient and selective mode multiplexers are crucial for practical MDM systems.

Purpose of the Study:

• To characterize an all-fiber 6-mode multiplexer for mode division multiplexing.
• To demonstrate the performance of mode selective couplers (MSCs) in enabling MDM transmission.
• To evaluate the feasibility of long-haul MDM transmission using the developed multiplexer.

Main Methods:

• Fabrication of mode selective couplers (MSCs) using polished-type fiber couplers to couple LP01 mode to higher-order modes (LP11, LP21, LP02).
• Characterization of the all-fiber 6-mode multiplexer using a wavelength-swept interferometer technique.
• Demonstration of mode division multiplexed transmission over 117 km fiber spans with an in-line multi-mode optical amplifier.

Main Results:

• The developed all-fiber 6-mode multiplexer, comprising LP11, LP21, and LP02 MSCs, was fully characterized.
• A pair of mode multiplexers exhibited a minimum mode dependent loss of 4 dB and mode group selectivity exceeding 15 dB.
• Successfully transmitted 6 modes of 120 Gb/s dual polarization quadrature phase shift keying signals across 30 wavelength channels over 117 km.

Conclusions:

• The all-fiber mode multiplexer demonstrates high performance in terms of loss and selectivity.
• The successful long-haul MDM transmission validates the potential of this technology for future optical networks.
• This advancement contributes to enabling higher capacity optical communication systems.