High ytterbium concentration Yb/Al/P/Ce co-doped silica fiber for 1-μm ultra-short cavity fiber laser application

The fiber has a Yb concentration of about 2.5 wt%, and the corresponding core absorption coefficient is measured to be ~1400 dB/m at 976 nm. The gain coefficient was measured to be approximately 1.0 dB/cm.

It is found that the Yb/Al/P/Ce co-doped silica shows a lower photodarkening-induced equilibrium loss of 52 dB/m at 633nm than the Yb/Al/P co-doped silica fiber of 117 dB/m. Using the heavily Yb3+-doped silica fiber, a compact and robust ultrashort cavity single-frequency fiber laser was achieved with a maximum output power of 75 mW and a linewidth of 14 kHz. Furthermore, a compact passively mode-locked fiber laser (MLFL) with a repetition rate of 1.23 GHz was also proposed using our developed Yb-doped fiber.