A higher-order-mode erbium-doped-fiber amplifier

Area of Science:

• Optics and Photonics
• Laser Physics
• Fiber Optics

Background:

• Higher-order modes (HOMs) in fiber amplifiers offer larger effective mode areas, enabling higher power operation.
• Previous HOM fiber amplifiers have faced challenges with mode purity and stability.
• Erbium-doped fiber amplifiers (EDFAs) are crucial for optical communications but are typically limited to fundamental mode operation.

Purpose of the Study:

• To demonstrate the first erbium-doped fiber amplifier operating in a single, large-mode area, higher-order mode (HOM).
• To achieve high-power output with significant gain in a compact fiber amplifier.
• To investigate the feasibility of using HOMs for high-power fiber laser and amplifier applications.

Main Methods:

• Utilized a high-power, fundamental-mode Raman fiber laser at 1480 nm as the pump source.
• Employed a UV-written, long-period grating to convert both pump and signal light to the LP(0,10) mode.
• Fabricated a 2.68 m long erbium-doped fiber amplifier designed for HOM operation.

Main Results:

• Achieved a maximum output power of 5.8 W at 1564 nm.
• Obtained more than 20 dB of signal gain.
• The effective mode area of the LP(0,10) mode was 2700 µm² at 1550 nm.
• The output mode profile remained undistorted even at the highest output power.

Conclusions:

• Successfully demonstrated the first single, large-mode area, higher-order mode erbium-doped fiber amplifier.
• The developed amplifier shows potential for high-power applications by maintaining mode quality.
• This work paves the way for future high-power fiber laser and amplifier systems utilizing HOMs.