Research On Millimeter-wave Optical Generator Based On Saw-up Wave Sweep

With the rapid development of information society, the mobile and broadband are the hot topics in the field of communication, which have become the goal of telecommunication in future. The existing wireless spectrum resources have been unable to meet the growing demand for broadband wireless services. To overcome the lack of radio spectrum resources, MmROF (millimeter-wave Radio over Fiber) has been proposed. MmROF (millimeter-wave Radio over Fiber) transmits millimeter-wave through optical fiber between base stations and central station in the wireless communication system, which combines millimeter-wave technology and fiber technology skillfully. It succeeds the flexibility and mobility of wireless communication, at the same time, it takes full advantage of the greater bandwidth provided by millimeter-wave, and overcomes the shortcoming of the atmosphere’s significant affecting to the millimeter-wave. As the vibration source and emissive source in the ROF system, the millimeter-wave generator affects the performance of the system and plays an important role. As one of the key technologies in mmROF, the millimeter-wave optical generator plays a vital role in the entire system.In this paper, the technique of the millimeter-wave optical generator is analyzed and simulated. The main work of the thesis can be listed as follows:1. Some basic concepts, principles and applications of the ROF system are introduced. According to the different signals transmitted in optical fiber, the baseband-over-Fiber, the IF-over-Fiber and the RF-over-Fiber transmission system are compared with each other. Also, their respective advantages and disadvantages are summarized. At last, the key techniques of ROF system are introduced.2. Current various mainstream schemes for millimeter-wave optical generation at home and abroad are analyzed, including direct intensity modulation techniques, external modulation techniques, up-conversion techniques and optical heterodyne techniques. The models of the technique are built from the basic principle step by step. Through analysis and comparison, the advantages and disadvantages of them are summed up.3. The OFM (Optical Frequency Multiplication) technology is introduced, and on this basis, a new improved method, which is millimeter-wave optical generator based on saw-up wave sweep, is put forward. In this scheme, DE-MZM (dual-electrode Mach-Zehnder modulator) is driven by the saw-up wave, two sidebands with40GHz frequency interval of the modulated light waves are filtered out respectively with two UFBG (Uniform Fiber Bragg Grating) in the central station, then the two sidebands are combined to form one optical signal and transmitted through optical fiber, after that, a40GHz millimeter-wave signal can be obtained at the PD (Photodetector).4. A theoretical analysis of this scheme is conducted, and the results prove its feasibility. Then the simulation is conducted, the simulation results answer to the theoretical analysis. The influence of various parameters on millimeter-wave generation is listed, including the laser line-width and the optical fiber length. At last, the characteristics of the system are summarized.