Er-doped photonic crystal fiber amplifier with 70 W of output power

We report for the first time, to the best of our knowledge, on a large mode area Er-doped photonic crystal fiber laser system. The fiber core had a diameter of 40 mu m and NA of < 0.04 leading to a mode field diameter of about 31 mu m around 1550 nm wavelength. More than 70 W of single-frequency output power at 1556 nm could be extracted using a master-oscillator power-amplifier scheme. Near diffraction limited output beam quality has been verified by measuring the TEM(00) content with a nonconfocal scanning ring cavity. (C) 2011 Optical Society of America