The persistent growth of interest in the middle infrared (MIR) is stimulating the development of sources and components. Novel waveguides and fibers for the efficient use of nonlinear effects in the MIR are being intensively studied. Highly nonlinear silica fibers have enabled record performances of highly versatile parametric processes in the telecommunication band. However, no waveguiding platforms (to our knowledge) have yet solved the trade-off among high nonlinearity, low propagation

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... and dispersion in the MIR. As single waveguide designs have not yet hit this particular optimal point, only pulsed-pumped demonstrations have been carried out, hindering any application requiring narrow linewidth, continuous-wave (c.w.) operation, or signal modulation. Here, we show MIR c.w. parametric amplification in a Ge 10 As 22 Se 68 tapered fiber. Leveraging state-of-the-art fabrication techniques, we use a photonic crystal fiber (PCF) geometry combining high nonlinearity and low dispersion, while maintaining single mode and low losses in the short-wave IR and MIR. We experimentally demonstrate 5 dB signal amplification and 3 dB idler conversion efficiency using only 125 mW of pump in the 2 μm wavelength range. Our result is not only the first c.w. parametric amplification measured at 2 μm in any waveguide, but it also establishes GeAsSe PCF tapers as the most promising all-fibered, high-efficiency parametric converter for advanced applications in the MIR.