Target-in-the-loop coherent beam combining based on an all-fiber structure

Area of Science:

• Optics and Photonics
• Laser Physics
• Fiber Optics

Background:

• Coherent beam combining (CBC) is crucial for high-brightness laser generation.
• All-fiber phase control offers compact solutions but struggles with π phase ambiguity.
• Existing methods require external mirrors, limiting scalability and robustness.

Purpose of the Study:

• To introduce and validate the target-in-the-loop (TIL) technique for all-fiber CBC.
• To address and compensate for π phase ambiguity in all-fiber systems.
• To decouple phase noise from amplifiers and atmospheric turbulence.

Main Methods:

• Implementing a TIL feedback structure with external measurement laser channels.
• Utilizing numerical simulations to demonstrate the principle of the proposed method.
• Constructing and testing a six-channel TIL CBC system.

Main Results:

• Successful compensation of π phase ambiguity and low-intensity phase shifts.
• Demonstration of decoupled phase noise and turbulence effects.
• Validation of the TIL technique in a practical all-fiber CBC system.

Conclusions:

• The TIL technique effectively resolves phase ambiguity in all-fiber CBC.
• The proposed system is scalable and compatible with high-power amplifiers.
• This approach provides a significant reference for future TIL CBC system designs.