Experimental study on the role of chromatic dispersion in continuous-wave supercontinuum generation

Abstract

The influence of chromatic dispersion on CW-pumped supercontinuum generation in km-long standard fibers is experimentally investigated. We perform our study by means of a tunable, high-power fiber ring laser pumping a dispersion-shifted fiber in the wavelength range of small and medium anomalous dispersion. Our results show that, at low input powers, chromatic dispersion plays a dominant role on nonlinear pump spectral broadening, giving rise to a broader spectrum when pumping just above the zero-dispersion wavelength of the fiber. At higher input powers, however, the width of the generated supercontinuum spectrum is mostly due to the Raman effect, hence more independent of the value of the chromatic dispersion coefficient. We show that, in this case, the optimum pumping wavelengths for supercontinuum generation are not so close to the zero-dispersion wavelength of the fiber as in the previous case. In these conditions, as the chromatic dispersion grows we can obtain square-shaped and high-power density spectra, which seem extremely promising for applications in optical coherence tomography.