Fiber Laser Coherent Array for Power Scaling of Single-Mode Fiber Laser

Coherent beam combining of many fiber lasers by the Y-shaped complex resonator method realizes both power scaling and spectral narrowing. The basic characteristics of this Y-shaped coherent array, scalability of power summation, and bandwidth narrowing property are presented. As high as 85% addition efficiency with only a few longitudinal-modes was obtained in an array of eight 10-nm bandwidth lasers coupled by fused fiber couplers. By threshold control of the constructive-interference supermodes, high-speed (>1 kHz), high-contrast-ratio (>100) coherent control of beam direction has also been demonstrated. Mass-free and reaction-free properties can realize high-speed laser-beam scanning, which will be quite useful in many applications such as material processing and space communications.