Tunable microwave and optical frequency comb generator with the aid of cascaded MZM structure

This paper proposes a tunable microwave and optical frequency comb generator utilizing a cascaded Mach–Zehnder modulator (MZM) Structure. Optical frequency combs are employed in a wide range of scientific and technological fields, including optical communication and optical signal processing. Microwave frequency combs have also garnered significant interest due to their promising applications in microwave communication and measurement. The proposed structure consists of a single-drive MZM cascaded with a dual-drive MZM, excited by radio frequency and local oscillator signals. This structure is capable of generating optical and microwave frequency combs by adjusting the bias and amplitude of the RF signal. We have developed an analytical model to describe the operation of this structure, taking into account the nonlinear behavior of the electro-optic modulators used in the MZMs. Using this analytical model, we can predict the power of each mixed frequency in the output spectrum. To achieve an optimal frequency comb in the optical or microwave output, which entails maintaining constant power for a specific number of frequency components, we systematically adjust applied voltages. This approach generates a comprehensive dataset containing power information for each mixed frequency, enabling us to identify the flattest output spectrum in the optical or microwave domain. Furthermore, we validate the analytical results using commercial simulation software.