High power fiber arrays for spectral and coherent beam combining of fiber laser and amplifier

Fiber lasers and amplifiers are capable of producing kilowatts of optical output power with diffraction-limited beam quality. We present high precision high power fiber arrays which can be used for coherent and spectral beam combining for scaling of fiber laser systems to high brightness and high power. The availability of CO2 laser-based fiber splicing systems that can control the position and size of the heating zone has opened up new possibilities in the splicing of multiple fibers (fiber arrays) to large optical elements. In our experiments we realized linear fiber arrays with PM and non-PM large mode area (LMA) fiber with no gap between the individual fiber channels (DC-PM-20/400 and DC-PM-25/250). The fibers were spliced to a large AR-coated fiber end cap. The misalignment of the PM axes of all fiber channels was less than ±1 degree and the inline tolerance of the fiber array was below ±2.5µm. Each fiber channel was tested up to an optical output power of 1kW.