Research on Linear Modulation Based on Electro-Optic Modulators and Microwave Photonic Frequency Conversion Technology

Radio-Over-Fiber (ROF) technology combines microwave photonics integration into wireless communications, integrating the high bandwidth of optical networks with mobility of wireless systems. The current paper focuses on linear modulation schemes and microwave frequency conversion in ROF systems. It addresses classical modulation schemes on electro-optic modulators, such as Double Sideband (DSB), Single Sideband (SSB), and Optical Carrier Suppression (OCS). The key parameters of microwave photonics, including link figure, noise figure, conversion loss, and dynamic range, are analyzed. A technique for linearizing the microwave photonic link by tuning the DC bias on Mach-Zehnder Modulators (MZMs) is proposed in this paper and shown to be viable by simulation. A frequency conversion system utilizing cascaded intensity modulators is also introduced, and system performance is enhanced by parameter optimization, i.e., DC bias and modulation index. The paper also presents the theory of photonic mixing with frequency doubling based on a Dual-Parallel MZM, providing insightful suggestions for future work in microwave photonics.