Flatness Improved Comb Generation by Electro-optic Phase and Mach-Zehnder Modulators Cascade

An optical frequency comb generator based on a cascade of electro-optic phase and intensity modulators is proposed and flat comb generation empirically demonstrated. For wide and equalized experimental combs, modulator driving conditions were carefully adjusted after conducting a theoretical performance analysis. Comb frequency spacing and central wavelength were defined by the modulating frequency (18 GHz) and the optical carrier wavelength (1550.8 nm), respectively. By using an ordinary phase modulator along with a dual-drive Mach-Zehnder modulator, an efficiently equalized 25-line comb was obtained. The experimental results agree with theoretical predictions.