| Microwave Photonic is an inter-disciplinary field of study which combines microwave engineering and photonic technology together. It is considered as a prospective subject who can find many applications in both military and civilian areas, such as remote broadband communication, radio astronomy, micro/millimeter-wave imaging and radar system. As an interdisciplinary subject, its research effect covers microwave photonic generator, microwave optoelectronic devices, and radio over fiber system. Under the supports of the National Nature Science Foundation of China, this thesis is devoted to investigate new prototype of microwave photonic generator and optical single sideband modulation with tunable optical carrier-to-sideband ratio (OCSR), by theory, simulation and experiment. The main innovative research efforts are summarized as follows:1. Two novel structures of impulse-radio ultra-wideband (IR-UWB) photonic generator have been analyzed and verified. Both two structures utilize the transmission function of typical modulators but in different modulation areas. In both two proposals, IR-UWB pulses can be obtained by using PM-IM mapping or pulse shape construction. By tuning the relative time delay between two paths of the Gaussian driving pulses, the IR-UWB pulse’s polarity and waveform can be switched easily.2. Two novel structures of periodic triangular-shaped pulse sequence generator based on continuous-wave laser modulation have been analyzed and verified. In both two proposals, optical carrier-suppression (OCS) modulation and fiber characteristic are employed, making the expression of output optical intensity approximately equals to the Fourier expansion of idea triangular-shaped pulses. In our work, periodic triangular-shaped pulse sequence with repetition rate twice of driving frequency can be obtained.3. Two improved structures of millimeter-wave photonic generator with frequency8-tupling have been analyzed and verified. Both two proposals employ two phase-uncorrelated lasers as source, which is characterized as totally different phase noise. In our work, we make improvement on the original prototypes (two-step heterodyne and feed-forward modulation) and introduce the idea of eliminating phase noise in millimeter-wave generation with frequency8-tupling. Since the frequency is independent on the wavelength division of laser source. Frequency stability can be guaranteed.4. A chirped fiber grating with triangular-shaped spectrum has been fabricated and utilized in RoF analog photonic link. By using the negative slop in the spectrum, optical single sideband (OSSB) modulation and a reduced OCSR can be obtained simultaneously, which improve the link sensitivity consequently.5. A polarize-maintained fiber grating (PM-FBG) has been fabricated and utilized in RoF analog photonic link. The functionality of PM-FBG is to separate and allocate optical carrier and sideband with orthogonal polarization. By simply tuning the inject polarization of OSSB signal, the target OCSR can be continuously tuned, which improve receiver sensitivity a lot. Besides, we also discuss the issue of the optimized OCSR in RoF analog photonic link when multi-subcarrier modulation is applied.6. A novel prototype of optical single sideband modulation with tunable OCSR has been proposed and verified. The proposal requires only one dual-parallel Mach-Zehnder modulator (DP-MZM) as the key component. By employing the three separate modulation units in the DP-MZM, optical single sideband modulation, optical carrier phase shifting and lightwave interference can be achieved at the same time. The OCSR can be simply tuned by changing the bias voltages of one single modulation unite, which can improve receiver sensitivity too. |
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