Design And Realization Of High Speed Signal Generator And Microwave Photonic Filter In ROF System

The urgently increasing demand of the transmission speed in wireless communication system causes the use of microwave carrier with higher frequency, which will result in an increasing number of regeneration stations and base stations, and also a sharply increasing cost of the wireless communication system. Radio over Fiber (ROF) technology appears to be a promising solution to overcome this problem in the wireless communication system. For the ROF technology, optical carrier which is modulated with the microwave signal is transmitted over fiber, and the microwave signal is recovered in the remote stations and radiated through antennas to reach the mobile targets. Based on the low cost, high bandwidth and electromagnetic immunity (EMI) properties of optical fiber, the ROF technology combines the advantages of optical fiber communications and wireless communications, possessing of a bright future. In this dissertation, two important devices in ROF system, high speed signal generator and microwave photonic filter, have been investigated. Based on Phase-Locked-Loop (PLL), a high speed sine signal generator with the speed of 2.58GHz, peak voltage of about 82mV and phase jitter of 15ps is achieved. The idea of microwave photonic filter comes from ROF system itself. The latter is to transport microwave signal over fiber, and the former is to process microwave signal directly in optical domain. By studying fiber ring based filters, we designed an asymmetric coupled ring filter with the Extinction Ratio of about 20dB, a microwave photonic filter with 700MHz Free Spectral Range (FSR), a tunable microwave photonic filter, and the cascade microwave photonic filters. Finally, experiment in a ROF model shows that the designed high speed signal generator and microwave photonic filter are useful and effective in ROF system.