We present a source of brilliant mid-infrared radiation, seamlessly covering the wavelength range between 1.33 and 18 ìm(7500–555 cm−1) with three channels, employing broadband nonlinear conversion processes driven by the output of a thulium-fiber laser system. The high-average-power femtosecond frontend delivers a 50 MHztrain of 250 fs pulses spectrally centered at 1.96 ìm. The three parallel channels employ soliton self-compression in a fused-silica fiber, supercontinuum generation in a ZBLAN fiber, and difference-frequency generation in GaSe driven by soliton selfcompressed pulses. The total output enables spectral coverage from 1.33 to 2.4 ìm, from 2.4 to 5.2 ìm, and from 5.2 to 18 ìmwith 4.5 W, 0.22Wand 0.5 W, respectively. This spatially coherent source with a footprint of less than 4m2 exceeds the brilliance of 3rd-generation synchrotrons by more than three orders of magnitude over 90% of the bandwidth.