| With coming of information age, the demand for broadband multimedia services is going up quickly. But the microwave spectrum is so congested that it can not provide enough bandwidth to support extra-broadband services. Development of millimeter -wave (mm-wave) band in wireless communication is a valid pass to larger capacity and higher data rate systems. 60GHz mm-wave system has the characteristics of broad bandwidth, small size equipment, and high sensitivity to atmosphere attenuation. In contrast, optical fiber provides with abundant spectrum resource and complete immunity to EMI (electromagnetic interference). Combination of mm-wave technology and optical fiber transmission technology can effectively extend transmission distance of mm-wave signal and reduce cost of the configuration. The study object of this thesis is 60GHz mm-wave Radio-over-Fiber (RoF) transmission system composed of center station (CS), base station (BS) and fiber transmission link between them. We focus on how to generate mm-wave carrier by optical technology, and how to realize a feasible 60GHz-RoF bidirectional transmission system, with especially simple scheme and cost-effective BS, based on commercial optical/electrical apparatus. The content of the thesis is organized into four parts as follows.The first part introduces the principle of optical frequency multiplying (OFM) technology. Starting with the physical and mathematical models of the dominating components involved in OFM systems, a method of using a periodical microwave signal to drive a optical phase modulator is presented to indirectly produce frequency-swept lightwave. From two aspects of theoretical analysis and software simulation, the principle of generating microwave/mm-wave and the process of delivering baseband data are explained. The simulation results reveal that there are much more harmonics than theoretical analysis. A theoretical fault in the published paper is pointed out.The second part studies the downlink of 60GHz-RoF transmission system based on OFM technology. Aiming at the problems of how to design frequency-swept lightwave and how to select comb-like optical filter in mm-wave OFM system, a thorough mathematical model is established. With time-domain analysis, the expressions of mm-wave carrier are derived under the conditions of three formats of sweeping signal and two optical filters of Mach-Zehnder/Fabry-Perot type, in which key system parameters are discussed to optimize the output signal. An implementation technique based on sinusoid scan of lightwave phase + Mach-Zehnder optical interfering + photo-detection & electrical filtering are formed, which can convert the information -modulated lightwave at CS directly into the modulated 60 GHz mm-wave at BS. The simulation results are agreed with theoretical analysis, which prove the scheme of the 60GHz-RoF transmission downlink is feasible. Furthermore, analysis on effect of laser linewidth on mm-wave RoF system employing OFM technology is fulfilled. Investigation on mm-wave amplitude fading along fiber distance due to optical fiber dispersion indicates that OFM technology benefits against optical fiber dispersion.The third part is devoted to research on the uplink of 60GHz-RoF transmission system. A solution of uplink transmission is proposed using pilot-tone technology, which by superimposing a pilot-tone sinusoid signal on the baseband information at CS, a continuous 58GHz mm-wave as a local reference oscillator needed by receiving downconversion at BS can be achieved by optical means. Then the baseband data is modulating the downstream lightwave. Optimizing compound signal of a pilot-tone and baseband information put on an intensity modulator is completed. In order to implement a low-cost light source of uplink at BS, Array-Waveguide-Guide (AWG) narrowband light injection to F-P lasers is developed. In these ways the RoF system design greatly simplifies the configuration of BS.The fourth part is realization of 40GHz-RoF bidirectional transmission system. An real 1550nm 40GHz/100Mbps RoF system platform, with creative Mach-Zehnder optical interferometer made by optical polarizer, polarization-maintaining fiber/couplers and temperature stabilizer, is designed and construted in hardware, by which the feasibility of mm-wave RoF system is experimentally proved. This is likely to be the first mm-wave RoF bidirectional transmission experiment system in China, which provides a sound foundation for setting up the mm-wave wireless LANs/access networks in future.The research work mentioned above has created 4 invention patents, and 10 papers.
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