Comparison of spectral beam combining approaches for high power fiber laser systems

Abstract

Spectral Beam Combination (SBC) of multiple fiber laser outputs has been shown to be an effective way to scale the power of fiber laser systems while maintaining near-diffraction-limited beam quality. The fiber SBC system maintains many of the key advantages of individual fiber lasers, such as high efficiency, excellent beam quality independent of output power and relaxed thermal management requirements. Several approaches to spectral beam combination have been demonstrated including single grating in linear oscillator, single grating in master oscillator power amplifier (MOPA), dual grating MOPA and dual grating ring oscillator configurations. Each of these variations has certain advantages in terms of the system design and fiber laser requirements. In this paper we analyze the different approaches and compare them in terms of combined beam quality, line-width requirements of the individual fiber laser channels, power scalability and system complexity. The results obtained using the different SBC approaches at Aculight are summarized in the context of this analysis.