| Radio over fiber (RoF) system plays an important role in transmission system's development. It has many advantages, such as light weight, small size, strong anti-jamming capability and confidentiality, making the base station and the transmission network much simplifier, to adapt the trend of the development of modern communication systems. In some study of military radar signal transmission, radio over fiber system is also widely used. So, the research on RoF system has great significance.The investigation of the RoF technology is divided into three parts. Firstly, the model of the RoF links is analyzed, the typical RoF links in our experiment and application are introduced, and the important devices of RoF links are described. Secondly, based on DFB laser, Mach-Zehnder Modulator (MZM), and Photodetector (PD), a RoF system is designed. The hardware circuitry system is fabricated and works properly. The system can keep a stable RF gain from-55℃to 70℃, making the gain of first-order signal stable in the best state. The electrical properties of system are also measured. Finally, we improve the design by adding the erbium-doped fiber amplifier (EDFA) for working in long distance transmission. We design the hardware system to achieve the any bias point control of the MZM, and apply it in a long distance transmission system, to improve the RF gain of the transmission system. This system also can work in a wide temperature range. Moreover, we propose that our system can also be used in some other RoF systems.The RoF system we mentioned above is a wide-bandwidth, large RF gain and stable transmission system. Our experiments show that, from-55℃to 70℃, our system can transmit the RF signal between 6GHz to 18GHz. By adding EDFA, and achieving the appropriate control of MZM, our system can be used in long distance transmission. |
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