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Mode-locked thulium-doped fiber laser with a narrow bandwidth and high pulse energy

We have demonstrated a mode-locked thulium-doped fiber laser with a narrow bandwidth and high pulse energy using a semiconductor saturable absorption mirror (SESAM). The laser generates sub-nanosecond pulses with a repetition rate of 39.8 MHz, average power of 150 mW, pulse energy of 3.8 nJ and spectrum width of 2 nm which should be attractive for pump sources to generate mid-infrared. To the best of our knowledge, this is the first report on a 2 μm mode-locked fiber-oscillator with a narrow spectral width and highest pulse energy in the all-anomalous-dispersion regime.