A tunable optical frequency comb source using cascaded frequency modulator and Mach–Zehnder modulators

Abstract In this work, we demonstrate a tunable optical frequency comb (OFC) source based on a cascaded frequency modulator (FM) and two Mach–Zehnder modulators (MZMs). The setup includes one FM and two MZMs, and a sinusoidal RF signal source that directly drive all these modulators. A Flat OFC source with a high number of comb lines, and tunable frequency spacing and center wavelength is analytically modelled and simulated. The results reveal that 51 comb lines with a frequency spacing of 25 GHz are generated when only FM is used. Thirteen of these lines have power variations of 1 dB. Next, by cascading FM with two MZMs, 127 comb lines are obtained. In addition, 101 of these lines have power variations of 1 dB. An optical frequency comb, with tunable frequency spacing ranging from 10 to 40 GHz is successfully generated. Moreover, the center wavelength of the generated OFC can be tuned from 1310 to 1610 nm.