Mode-selective amplification in a large mode area Yb-doped fiber using a photonic lantern

Area of Science:

• Fiber optics
• Laser physics
• Photonics

Background:

• Large mode area (LMA) fibers are crucial for high-power fiber lasers.
• Controlling spatial modes in LMA fibers is challenging but essential for beam quality.
• Yb-doped fibers are widely used gain media in fiber lasers.

Purpose of the Study:

• To demonstrate selective spatial mode amplification in a few-mode, double-clad Yb-doped LMA fiber.
• To investigate simultaneous amplification of different spatial modes and resulting mode competition.
• To develop a reconfigurable architecture for spatial mode control in LMA fiber amplifiers.

Main Methods:

• Utilized an all-fiber photonic lantern for selective spatial mode excitation.
• Employed a few-mode, double-clad Yb-doped LMA fiber as the gain medium.
• Measured amplification gain for individual and simultaneous spatial modes (LP01, LP11a, LP11b).

Main Results:

• Achieved multi-watt output power with high spatial mode selectivity.
• Observed gain values exceeding 12 dB for individual LP01, LP11a, and LP11b modes.
• Investigated mode competition during simultaneous amplification of LP01+LP11a and LP11a+LP11b modes.

Conclusions:

• The proposed architecture enables reconfigurable spatial mode excitation in LMA fiber amplifiers.
• Demonstrated selective amplification of multiple spatial modes with high gain.
• This work presents a promising method for dynamic spatial mode control in high-power fiber lasers.