Regenerative Feedback Opens the Scaling Bottleneck of Passive Fiber Laser Arrays

摘要

This report examines the effect of adding individual reflectors to elements of fiber laser arrays with passive beam combining architectures. Our analysis demonstrates that this regenerative feedback induces a nonlinear phase shift of the amplified light relative to the "cold-cavity" phase shift acquired without the individual reflectors. This results in a clustering of the phases at the array output and offers one method to significantly improve the array coherence of large passive arrays. The excellent beam quality and efficiency offered by fiber lasers at high powers has made them leading candidates as directed energy sources. Today a single-mode fiber laser with 10 kW output power has been realized [1] and it is expected that a high-quality 30-40 kW source is achievable [2], yet this still falls far short of the 100 kW (or greater) level required in many military-relevant applications.