Pump Wavelength Flexible, Continuous-Wave Fiber Supercontinuum Using Two-Stage Spectral Broadening

Low-power continuous-wave (cw) pumped supercontinuum sources exhibit poor spectral flatness and high sensitivity to the position of pump-wavelength with respect to the zero-dispersion of the nonlinear fiber. We propose a technique to overcome these limitations by the simple addition of a section of transmission fiber (such as Corning LEAF) before the nonlinear broadening stage. The pump incoherence introduced by this fiber in the C-band allows for a smooth, equalized, input wavelength flexible supercontinuum at low powers. With the proposed two-stage spectral broadening, we have successfully demonstrated for the first time, a cw pump wavelength agile all-fiber supercontinuum module with spectra spanning from 1300 nm to 2000 nm using relatively short lengths of nonlinear fiber. Similar supercontinuum is obtained for output powers from 80 mW up to a maximum in this work of 550 mW making it an ideal source for broadband low-power applications.