Performance Analysis of Mach-zehnder Modulator in Radio over Fiber Systems

Radio over Fiber (RoF) is a next generation wireless broadband Internet access technology. In Radio over Fiber system the radio signal is generated at the central station is modulated on to light and transmitted over optical fiber cable to various base stations. The base station has to convert the optical signal to an electrical signal, amplify and transmit it. Modulation of RF signal onto light is a key function of the system. Both direct and external modulations are employed in RoF systems. External modulators are preferred in high performance RoF systems due to many advantages. The Mach-Zehnder Modulator (MZM) is a versatile external modulator which makes it attractive for Radio over Fiber systems. By using different combinations of applied electric fields, the Mach-Zehnder modulator can be used to generate phase modulation, amplitude modulation, or a number of other modulation formats. Here both simulative and experimental study of Radio over Fiber (RoF) system employing the Mach Zehnder Modulator (MZM) as external modulator is done. The modulator performance in various configurations are analyzed in this paper.