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.
We describe a three-channel, spectrally beam combined (SBC), 1-&mgr;m fiber laser that features a SBC power combining
efficiency of 93%, versatile master-oscillator, power-amplifier (MOPA) fiber channels with up to 260 W of narrowband,
polarized, and near-diffraction limited output, and currently produces 522 W of average power with a dispersed (non-dispersed)
beam quality at 522 W of 1.18x (1.22x) diffraction limited. To our knowledge, these results represent the best combination of output power and beam quality achieved by SBC to date.
We describe a three-channel, spectrally beam combined (SBC), 1-&mgr;m fiber laser that features a SBC power
combining efficiency of 93%, versatile master-oscillator, power-amplifier (MOPA) fiber channels with up to 260 W
of narrowband, polarized, and near-diffraction limited output, and currently produces 522 W of average power with
a dispersed (non-dispersed) beam quality at 522 W of 1.18x (1.22x) diffraction limited. To our knowledge, these
results represent the best combination of output power and beam quality achieved by SBC to date.
We report on progress toward power scaling Yb fiber lasers beyond kW levels by an efficient and versatile architecture that maintains near diffraction limited beam quality. For this work, power scaling is performed at two distinct levels. The first utilizes a diffraction grating to spectrally beam combine (SBC) the output from several master-oscillator, poweramplifier (MOPA) fiber lasers with a goal of producing high quality combined beams with > 1 kW of power. The second involves scaling individual MOPA outputs to > 200 W, thereby reducing the number of lasers required for SBC. As a first step toward reaching these goals, we have developed Yb fiber MOPAs producing up to 208 W of polarized, narrow band, and near diffraction limited output and have demonstrated two-channel fiber laser SBC with a power combining efficiency of 93%, a combined beam power of 258 W, and a dispersed axis M2 of 1.06. These results represent a significant advance in high brightness, spectrally beam combined laser systems.
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