Photonic generation of 32-tupled millimeter wave using four-stage cascaded Mach–Zehnder modulators

With the rapid development of 5G mobile communications, the dependence of massive devices and services on microwave frequency bands has led to the congestion of available spectrum. It is crucial to study higher-frequency millimeter waves (MMVs). We propose a new 32-fold frequency MMW generation scheme based on four cascaded Mach–Zehnder modulators (MZMs) and adopt a simple wireless optical fiber (ROF) link structure. The four MZMs work at the maximum emission point, suppress odd-order optical sidebands, and retain even-order optical sidebands. The radio frequency (RF) driving voltage of the adjacent two-stage MZM differs by 45 deg, and the nonlinear characteristics and phase difference of the MZM are used to achieve step-by-step multiplication of the signal frequency. The required ±16-order sidebands are generated by selecting the appropriate modulation index, bias point, and phase shift. Then, the optical attenuation and tuning technology and optical phase shifter suppress the center carrier. We conduct in-depth mathematical analysis and simulation verification of the proposed scheme. The simulation results show that by driving the MZM with a 5 GHz RF signal, a 160 GHz MMW signal with an optical sideband suppression ratio of 54.89 dB and an RF sideband suppression ratio of 42.8 dB is obtained. These results demonstrate the advantages of the proposed scheme in achieving high multiplication factor and high signal purity, making it very suitable for application in existing and next-generation communication systems.