Fig. 1. Basic setup of an all-fiber gain-switched fiber laser.

Fig. 2. Schematic illustration of the difference between gain-switching and Q-switching. The upper panel shows the evolution of their upper laser level populations during a single pulse generation, and the lower panel shows the corresponding emitting characteristics.

Fig. 3. Left panel is the simplified energy diagram of Tm3+ ions; different pump schemes and their corresponding transitions are represented by black arrows, and the red arrow is the laser transition. Right panel is the temporal features of a numerical simulation on a gain-switched Tm-doped fiber laser. To demonstrate the detailed information of the pulses induced by the pump wavelengths at 1053 and 1550 nm, we enlarged the content inside the dashed line box.

Fig. 4. Temporal characteristics of a gain-switched Tm-doped fiber laser with a hybrid pump scheme: a pulsed 1.5-μm pump source and a CW 793 nm LD pump. (a) and (b) The situations when the launched CW pump power is at a low and a high level, respectively.

Fig. 5. Supercontinuum induced by gain-switched pulses. A 10 m single-mode fiber was spliced to the gain-switched Tm-doped fiber laser, and a supercontinuum spanning over 200 nm can be observed with an average power spectral density of >30  mW ⋅ nm−1.

Table 1. Reported Output Features of the Gain-Switched Fiber Lasers