Generation of wideband and flat supercontinuum over a 280-nm spectral range from a dispersion-flattened optical fiber with normal group-velocity dispersion

Aiming at wideband and flat supercontinuum generation (SC) from optical fib ers in the 1.55-mu m wavelength region, we study both experimentally and th eoretically how SC spectra are influenced by group-velocity dispersion (GVB ) of fibers. In the anomalous GVD region, since the peak power of pump puls es is kept high during propagation through the fiber by the higher-order so liton effect, the Raman effect has an adverse effect to flat and wideband S C generation. In the zero GVD region, the interplay of the third-order disp ersion (TOD) and the self-phase modulation splits the SC spectrum into two main components. On the other hand, in the normal GVD region, nevertheless the SC spectrum broadens wider and smoother than those in anomalous and zer o GVD regions, it is still asymmetric when TOD of the fiber can not be igno red. From these results, we find that a dispersion-flattened fiber with nor mal GVD is the most suitable for fiat and wideband SC generation. A 280-nm wide SC spectrum with the spectral-density fluctuation less than 10 dB is a ctually generated from such a fiber.