Gain-switched and mode-locked 2 μm Tm/Ho-codoped fiber laser

Gain-switched by 1550 nm pulsed laser, a simultaneously gain-switched and mode-locked Tm/Ho-codoped fiber laser with a central wavelength of 1958 nm is obtained. The pulse train contains many mode-locked sub-pulses within one gain-switched pulse envelope. Using this pulsed laser as a seed source, a flat supercontinuum (SC) is generated in a Tm-doped fiber amplifier where Tm-doped fiber is both the non-linear and gain medium. For the average output power of 2. 17 W, the observed spectrum covers the spectral range of 1953 to 2593 nm with a 10 dB bandwidth of 640 nm and the long wavelength edge of SC spectrum is extended to 2750 nm.