| Microwave photonics is a multi-disciplinary research area which studies the interaction of microwave and optical signals for applications such as microwave/millimeter-wave signal generation, distribution, control and processing by means of photonics. Typical applications of microwave photonics include Radio-over-Fiber (RoF), optically controlled phased array radar, and so on. In this thesis, the generation and transmission of high-performance microwave/milimeter waves and their applications in RoF systems are investgated systematically based on microwave photonics. Several original results are obtained, promoting the research and application of microwave photonics technology. The main works and original results are summarized as follows:Firstly, we proposed and experimentally demonstrated a novel scheme to generate polarization-insensitive optical millimeter-wave (mm-wave) wavelength-division-multiplexing (WDM) signals based on four wave mixing (FWM) in the semiconductor optical amplifier (SOA) and carrier suppression in the external modulator. In the scheme, two copolarized pumps and a WDM signal are mixed in the SOA, and the quadruple frequency mm-wave signal is then obtained by using an optical filter to remove one sideband. The experimentally generated 40GHz optical mm-wave signal is similar to the single-sideband mm-wave signal, which can be used to fulfill a nearly dispersion-free long-distance transmission. Our experiment demonstrates a downstream signal delivery over a 20km fiber with power penalty less than 1 dB.Secondly, we proposed and experimentally demonstrated a novel scheme to generate optical mm-wave dense wavelength division multiplexing (DWDM) signals with four time frequency of the local oscillator by using only one external modulator. By incorporating the proper direct current (DC) bias on the external modulator to suppress the first order sideband in central office (CO), and using optical filtering technique to separate the optical mm-wave and optical carrier in the base station, the DWDM optical millimeter-wave (mm-wave) signals are generated with four times frequency of the local oscillator (LO) signal. In the scheme, the lower frequency device such as RF source, electrical mixer, and optical modulator can be used to generate high frequency optical mm-wave DADM signals, which significantly reduce the cost of the DWDM ROF system. We have experimentally demonstrated four-channel DWDM optical mm-wave signal generation with a repetitive frequency up to 40GHz by 10GHz LO, and down-stream signal delivery over 20-km fiber with 0.7dB power penalty.Thirdly, motivated by the potential applications of terahertz communication, terahertz phased-array radar and so on, we have explored and experimentally demonstrated a feasible way to generate low-frequency terahertz waves using microwave photonics technology. In our experiment, the stable 0.1THz wave with a desired carrier suppression ratio is obtained by using a Mach-Zehnder modulator and an Interleaver.Finally, we explore the application of the proposed technologies for mm-wave genreation in RoF systems. As a principle contributor, the author has participated in the development of the 10-60GHz RoF systems. The developed RoF systems can fulfill the stable, reliable and high-performance modulation, propagation, transmission and receive of optical mm-wave signals. The peer experts judge the developed RoF systems as an advanced production in the world as a whole, important for promoting the utility of RoF technology. There are four original results in the developed RoF systems, including the aforementioned two technologies proposed by the author.
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