| Microwave photonics is an interdisciplinary of photonics and microwave, so that it combines the advantages of both of them. Microwave photonics focuses on the generation, processing and conversion of microwaves and millimeter-waves using optical method as well as distribution and transmission of the m by fiber, which has important research value and wide development trend. As a hot research area in microwave photonics, microwave photonic frequency conversion has attracted attention of many researchers all over the world, who have come up with kinds of conversion scheme. Some schemes prefer to the simpleness, some aim at flexibility and some pay attention to optimizing one or some indexes of the system. In a word, microwave photonic frequency conversion is developing towards having good performance and diversified function. This dissertation proposes a scheme which is in accordance with the trend of microwave photonic frequency conversion. It has a good performance on the conversion efficiency, meanwhile it is combined with the transmission of the signal. By some simple settings, the scheme can suppress the dispersion without losing of the conversion efficiency, so that it does no harm to the signal.In this dissertation the main decices is introduced, especially the modulator whose type will affect the system’s structure and performance. Meanwhile, the modulation formats have an important influence on all the microwave photonic link, so three modulation formats are introduced, namely double side band, single side band and optical carrier suppress modulation. In this dissertation some indexs of microwave photonic frequency conversion are introduced with some specific schemes, among witch the most important are frequency conversion efficiency and spurious free dynamic range. In taday’s experimental study, the highest conversion efficiency is above 24 d B than the earlist microwave photonic frequency conversion scheme,and the largest spurious free dynamic range is more than 120 d Bc/Hz4/5.A microwave photonic frequency conversion scheme which can suppress the influence of the fiber dispersion in addition with a high conversion efficiency is studied in this dissertation.The theory is connected with experiment in order to examine the scheme.In the experiment it is clear to see the influence of the fiber dispersion by with and without the fiber. Further more, by comparision it is easily to see that the scheme can suppress the influence of dispersion just by tuning the DC bias of the modulator. At last the scheme is used in the vector signal up-conversion and transmission experiment, in which a 20 Mbaud 16-QAM signal is up-converted from 2.4GHz to 16 GHz and transmitted over a 25 km long fiber. At the receiver, the EVM is deteriorated by 0.8%.The scheme proposed in this dissertation has a high conversion efficiency and is easy to adjust to suppress the fiber dispersion in experiment; besides it is so stable, that it can be applied in the engineering practice. |
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