10 GHz-spaced, 20 THz-wide comb generation from CW light using Mach-Zehnder modulator based comb generator and dispersion-flattened dispersion-decreasing fiber

Optical comb generation is important for coherent WDM or OFDM systems that extremely improve spectral efficient of WDM systems. Mode-locked lasers are typically used for supercontinuum generation. However, the mode-locked lasers have some drawbacks in stability and tunability. A Mach-Zehnder modulator (MZM) based comb/pulse generator is good candidate for a comb source with high stability and high accuracy. This system has tunability in both the spacing and wavelength, and can operate with alignment-free and turn-key starting. Although obtainable bandwidth of the comb signal is typically several hundred gigahertz, it can be broadened into the order of terahertz by using nonlinear fibers. In this paper, broadband optical comb generation from a CW light using the MZM-based flat comb generator (MZ-FCG) and a dispersion- flattened dispersion decreasing fiber (DF-DDF) is reported.