The coherent combining (CBC) of laser systems allows the average laser power to be scaled far beyond 100 kW while still maintaining excellent beam quality (M² ~ 1) in the combined beam, thus enabling extremely high (spatial) laser peak intensities. This opens up new fields of laser applications in aerospace, material processing, defense, space missions and even inertial confinement fusion.

A key component of this approach is the CBC beam combiner unit, which must be designed to withstand these extremely high laser power levels. FiberBridge Photonics designs and manufactures unique high-precision CBC beam combiner units that are able to achieve diffraction-limited wavefronts and that have no observable thermal impacts on the combining process, even under extreme high-power operation.

Ultrafast phase modulators enable control and compensation of the relative phase between the channels, allowing coherent superposition of all channels in the far field. Additionally, output beam shaping is also possible, enabling an even broader range of applications, including material processing, laser fusion and counterspace applications. In comparison to spectral beam combining, CBC laser systems can typically achieve much higher laser peak intensities due to their superior beam quality.* The integrated phase control unit in a CBC laser system also allows for ultrafast beam steering and wavefront corrections, which are essential tools for mitigating atmospheric turbulence in real-world applications. The unique advantage of FiberBridge Photonics lies in our ability to offer a complete vertical integration of these systems, including the seed laser, fiber components, fiber-based beam splitter, high-power amplifier and phase correction units.

Currently, up to 127 laser channels can be combined within a highly compact beam combiner unit, with the option of scaling the system to 169 or even 217 channels. Increasing the number of channels, and therefore the overall laser power, does not degrade beam quality; this is typically in stark contrast to spectral beam combining. In fact, scaling up the number of laser channels and thus the total optical power offers several advantages. A greater number of laser channels increases the failure resilience of the system, enables more freedom and efficiency – for example in atmospheric turbulence control, beam shaping and ultra-precise beam steering – and ultimately also allows for more relaxed optical power requirements per individual fiber amplifier. For example, a 100 kW system with 127 channels enables the use of amplifiers delivering less than 1 kW output power per channel.

The mechanical and optical precision and thermal behavior of the beam combiner unit are the crucial factors that determine both the combining efficiency and the beam quality of the laser system. FiberBridge Photonics offers cutting-edge CBC beam combiner solutions as well as complete CBC high-energy laser systems with unrivaled accuracy and robustness. Our vertically integrated in-house technology and expertise give us full control and flexibility, so we can offer tailored solutions for individual customer applications.

Please use the following links for more information:

• CBC high-energy lasers for directed energy (counter-drone solutions)

• Ground-based high-energy lasers for counterspace applications

• Laser-based fusion based on CBC

• Wireless Power Beaming

*Based on typical estimated SBC beam quality between 30 kW–100 kW of M²∈ [1.7,3.0].