SBC is an incoherent approach for combining multiple fiber laser channels into one high-power beam. This method bypasses the complex phase stabilization required in coherent beam combining, significantly simplifying the system. The multiple fiber laser channels are spectrally separated from each other and can thus be combined by a wavelength selective element or grating. A typical configuration consists of a linear fiber array and a spectrally dispersive element such as a grating to overlap the spatially separated individual channels into a combined output beam.

The most promising approach for power scaling relies on a beam combiner unit having an extremely precisely arranged hexagonal fiber array based on a tiled aperture approach (i.e., side-by-side combining). More than 200 channels can be coherently combined within a compact beam combiner head not larger than a commonly used QBH connector. Each fiber channel in the hexagonal array can be operated with an ytterbium (1µm), erbium (1.5µm) or thulium (2µm) narrow linewidth amplifier. The beam delivery fibers that connect the fiber amplifier with the beam combiner need to be carefully chosen to mitigate stimulated Brillouin scattering (SBS) and maintain beam quality. Ultrafast phase modulators enable control and compensation of the relative phase between the channels, allowing for a coherent superposition of all channels in the far field.

FiberBridge Photonics is a world-leading manufacturer of ultra-precise, monolithic fiber arrays with more than 120 channels that are tested up to 3 kW per channel. This enables laser systems beyond the 100 kW regime.

These kinds of CBC systems typically achieve up to 75% combining efficiency with excellent beam quality. Phase control also allows for ultrafast beam steering or wavefront corrections – an essential tool for the correction of atmospheric turbulences in real-world applications. Additionally, beam shaping of the output beam (coherent and incoherent) is also possible, and enables an even wider range of applications, including dynamic material processing (e.g., 3D printing or welding).

This technique has demonstrated impressive results – achieving over 20 kW of average power while maintaining excellent beam quality. Furthermore, systems combining more than 30 individual channels have been successfully implemented. While the performance of each individual laser source is essential, the precision of the fiber array is paramount. The position and angular accuracy of each fiber within the array directly impact the quality of the combined beam.

FiberBridge Photonics offers cutting-edge solutions for SBC from individual fiber components to complete high-power laser systems based on narrow linewidth fiber amplifiers. Our linear fiber arrays are a key component for achieving extremely efficient systems in terms of size, weight and optical power level. FiberBridge Photonics also offers an interface unit for a full fiber-based connection between the linear fiber array and the narrow linewidth fiber amplifier.

The control of the whole process chain – from component to system level – allows for exceptional flexibility in tailoring solutions to meet the specific requirements of individual customer applications.

For detailed information and customized solutions, please contact us for further details!