A high power 1030 nm ytterbium doped fiber laser with a near diffraction limited quality using a 20/400 μm active fiber

A 1030 nm ytterbium doped fiber laser (YDFL), made by using a 20/400 μ m YDF, was studied both theoretically and experimentally in this article. From the theoretical point of view, it is found that the optimum length for the active fiber with higher than 30 dB suppression of amplified spontaneous emission (ASE) effect is about 7.3 m. However, an output beam with a diffraction limited quality ( M 2 = 1.16) and 735 W power with a slope efficiency of 77% and over 30 dB of signal to noise ratio without any sign of ASE was extracted from this YDFL.