Fig. 1. Experimental setup of the germania-fiber-based MIR SC laser. TDFA, thulium-doped fiber amplifier.

Fig. 2. (a) Spectral evolution of the generated SC for a germania fiber length of 0.2 m. The curves are offset vertically for clarity. The offset is 10 dB for every two neighboring curves. (b) Pump laser spectrum and SC spectra comparison for maximal output power for different lengths of germania fiber (0.3, 0.2 and 0.1 m, left-hand axis) and measured attenuation curve of the used germania fiber (right-hand axis). SC power and corresponding pump power are shown in parentheses. Inset depicts the beam profile captured by a pyroelectric array camera.

Fig. 3. SC power with respect to the pump power. Inset depicts the picture taken in the experiment when the SC power reached 44.9 W.

Fig. 4. SC power stability test for over 1 h. Inset gives the zoomed power fluctuation from 5 to 70 min after the test began.

Table 1. Overview of SC generation in germania fiber with output power more than 1 W.