Frequency Comb-Based Seed Laser Architecture With Improved Brillouin Performance for Spectral Beam Combining of Narrow-Linewidth Lasers

This study presents a novel approach to spectral beam combining for achieving high output powers with a compact, single module seed laser source based on frequency combs. By utilizing an electro-optic comb generator that can adjust the repetition rate and central wavelength, this system generates numerous wavelengths from a single laser, serving as individual laser sources for spectral beam combining. Additionally, the system can incorporate a single line-broadener for all channels together for suppressing stimulated Brillouin scattering (SBS). A de-multiplexer is used to separate distinct wavelengths into individual fiber ports. By employing external phase modulation with white noise, the system can adjust the linewidth from a single frequency to 4 GHz. Furthermore, superior SBS control is achieved by tailoring the lineshape in the de-multiplexer, which reduces feedback-assisted SBS. With the customized lineshape, the SBS threshold of the system increases by $>$50%. By mitigating the complexities of conventional spectral beam combining, such as the use of multiple laser sources and the requirement for each laser to have a current and temperature controller, in addition to a line broadener, this innovative approach presents a cost-effective and less complex alternative for power scaling.