All-fiber Q-switched and self-mode-locking Er3+/Yb3+-codoped ring laser

A high efficiency Q-switched and self-mode-locked Er 3+ /Yb 3+ co-doped fiber ring laser with a Mach-Zehnder interferometer (MZI) is proposed. The fiber laser with threshold of 126.84 mw and linewidth of 0.06nm has been demonstrated. The average power of 62.6mW, the peak power of 1231.8mW of the Q-switched giant pulses with the pulse duration of 2.6μs can be achieved. It is found that in order to generate Q-switched giant pulses, different repetition frequency must be selected as pumping power is changed. This phenomenon is observed for the first time to our knowledge. In the experiment, it is also found that stable passive Q-switch pulses can be observed, which waveform is not the same with the different pump power, although the arms lengths of the interferometer is not changed. When the absorbed pumped power is increased to 591.8mW, a self-mode-locking pulse can be formed and it is given a detailed theoretically illustration in this paper.