Photonic lantern adaptive spatial mode control in LMA fiber amplifiers

Area of Science:

• Optical Engineering
• Fiber Optics
• Laser Technology

Background:

• Large mode area (LMA) fiber amplifiers are crucial for high-power laser systems.
• Controlling spatial modes in LMA fibers is challenging due to multimode operation.
• Existing methods for mode control can be complex and inefficient.

Purpose of the Study:

• To demonstrate adaptive-spatial mode control (ASMC) in few-moded LMA fiber amplifiers.
• To achieve a single fundamental mode output with high fidelity.
• To utilize an all-fiber-based photonic lantern for mode control.

Main Methods:

• Utilized an all-fiber photonic lantern to couple light into a few-moded LMA fiber amplifier.
• Employed three single-mode fiber inputs to inject a superposition of modes.
• Actively adjusted the relative phase of the single-mode inputs for coherent combination.

Main Results:

• Achieved adaptive-spatial mode control in a few-moded LMA fiber amplifier.
• Demonstrated near-unity coherent combination of input modes.
• Successfully generated a single fundamental mode at the output.

Conclusions:

• ASMC using a photonic lantern is an effective method for mode control in LMA fiber amplifiers.
• This technique enables efficient generation of a single fundamental mode output.
• The all-fiber approach offers a practical solution for high-power fiber laser systems.