Output pulses from an ultrafast holmium-praseodymium co-doped fiber ring laser are spectrally broadened in different highly nonlinear chalcogenide fibers. Moderate levels of broadening are achieved in step-index fibers and the effect is utilized for nonlinear pulse compression. Much larger broadening factors can be observed in suspended-core fibers and polymer-protected robust all-chalcogenide microwires. Under optimized conditions, an ultra-broadband supercontinuum spanning from 2 – 12 μm is generated.