Investigation of optical frequency comb generation with sharp spectral edges using external modulators

We evaluate the operating conditions of the cascaded intensity and phase modulators used for the generation of the optical frequency comb lines having the sharpest spectral edges for a given spectral flatness. These operating conditions (to achieve the sharpest spectral edges) are different from those for the best spectral flatness. By operating the cascaded intensity and phase modulators with these conditions, we can place multiple sets of frequency comb lines as close as possible in wavelength, and thus improve the spectral efficiency of the system.