Passive mode-locked Yb3+-doped fiber ring laser

Using ultra-highly doped Yb3+ fiber as gain medium for the first time in China, pumped by 974 nm LD and passively mode-locked by nonlinear polarization rotation effect of the fiber, stable mode-locked fiber ring laser is obtained. The mode-locked threshold power of the laser is 150 mW and the output power is 26 mW with a pump power of 220 mW. The center wavelength of the mode-locked pulse is 1 046 nm with 3 dB bandwidth of 6.01 nm, 20 dB bandwidth of 16nm, pulsewidth of 22 ps and repetition rate of 20 MHz. Compared with similar fiber lasers, the laser has higher output power and better stability.