Efficient and robust spatial-to-fiber coupling-with scalability to multimode quantum networks via the cascaded...

Area of Science:

• Optics and Photonics
• Control Systems Engineering

Background:

• Free-space to fiber optic coupling efficiency is limited by environmental factors like beam displacement and jitter.
• This instability is a major bottleneck in high-precision optical transmission systems.

Purpose of the Study:

• To develop an adaptive feedback control system for robust optical coupling.
• To achieve both rapid response and long-term stability in optical transmission.

Main Methods:

• A cascaded adaptive feedback control system was integrated into the optical path.
• A power-feedback-based ramp-up algorithm dynamically adjusted piezoelectric-driven mirrors for autonomous beam alignment.
• The system was tested on a rubidium Raman photon source experimental platform.

Main Results:

• Optical coupling efficiency improved from <1% to >80% (multimode) and >70% (single-mode) within 10-20 seconds.
• The system achieved long-term stable transmission within 65-70 seconds.
• Real-time monitoring suppressed coupling attenuation due to beam jitter.

Conclusions:

• The proposed system effectively addresses environmental disturbances in optical coupling.
• It offers a practical solution for efficient coupling in demanding quantum, sensing, laser communication, and optical sensing applications.
• The method balances response speed and transmission stability without complex mode optimization.