Ring-core fiber-based coupling and amplification of OAM modes: realizing efficient second-to-first and...

Area of Science:

• Optical Engineering
• Telecommunications

Background:

• Orbital angular momentum (OAM) multiplexing offers potential for increased optical communication capacity.
• Efficient amplification of OAM modes is crucial for practical implementation of mode-division multiplexing (MDM) systems.

Purpose of the Study:

• To design and demonstrate fully fiber-coupled OAM mode amplifiers.
• To achieve high gain amplification for both second-to-first and second-to-second order OAM modes.

Main Methods:

• Utilized side-polishing and bonding techniques with dual ring-core erbium-doped fibers (RC-EDFs).
• Optimized structural parameters and ring spacing of RC-EDFs for mode matching at 1550 nm.
• Developed two types of all-fiber in-line OAM amplifiers.

Main Results:

• Achieved power coupling and amplification of OAM modes between RC-EDFs.
• Demonstrated amplification for both second-to-first and second-to-second order OAM modes.
• Both amplifier designs achieved a gain exceeding 30 dB.

Conclusions:

• The developed all-fiber OAM amplifiers provide a foundation for separating and amplifying higher-order OAM modes.
• This advancement supports the application of fiber-coupled amplifiers in high-capacity MDM optical communication systems.