Spectral beam combining of Yb-doped fiber lasers with high efficiency

Spectral beam combining is a power scaling concept for fiber lasers, where several individual laser beams with different wavelengths are overlapped utilizing a dispersive element. We present a combination of three master-oscillator power-amplifier fiber laser systems to a total power of 153 W. Due to the employment of single-polarization low-nonlinearity photonic crystal fibers in the main amplification stages a combining efficiency as high as 95% has been realized. The measured beam quality of M-2 = 1.2 for each laser does not decrease for the combined beam. Thus this setup provides excellent opportunities for brightness enhancement. Additional considerations for further increase in power are made. (c) 2007 Optical Society of America.