1 μm mode-locked fiber laser based on Nd3+-doped silica fiber

We demonstrate a mode-locked fiber laser in the all-normal-dispersion (ANDi) region at 1064 nm wavelength using a homemade Nd3+-doped silica fiber (NDF) as the gain medium. The Al3+/Nd3+ co-doped silica core glass with 18300 ppm Nd3+ doping concentration was fabricated by the modified sol-gel method. The NDF drawn with the rod-in-tube method has a core of 4 μm in diameter and numerical aperture (NA) of 0.14. The measured attenuation and group velocity dispersion of the NDF is about 1 dB/m and -36 ps/km/nm at 1064 nm. 18 mW average power is measured at the fiber laser output with a pulse duration of 5.75 ps and pulse energy of 1.14 nJ. A 7.2% slope efficiency is achieved, which is the highest reported in all NDF based ANDi laser so far, to the best of our knowledge.