Research On Microwave Triangle Wave Generation Technology Based On Photonic Technology

In recent years,microwave photonics has attracted more and more scholars because microwave photonics technology has characteristics including that high frequency,wide bandwidth,easy to reconfigure etc.It is able to overcome the problems that traditional electronics method is difficult to generate high frequency microwave signal due to the electronic bottleneck.So,photonics technology is widely used in the radio frequency communication,electronic measurement,etc.In this thesis,we expounded the microwave arbitrary waveform generation based on photonics technologies,especially,for the triangular waveform.The operation principle and simulation are analyzed in detail.We proposed to schemes to generate triangular microwave waveform.The first one is the triangular signal generation by using polarization orthogonal optical time-domain synthesis.In the scheme,a properly modulated sinusoidal signal,based on the characteristics of a MZM,is divided into two orthogonal channels by a polarization beam splitter.Two optical channels have a specific phase delay by tuning an ODL in one channel,and are recombined by a polarization beam combiner.Then a triangular waveform signal can be obtained after photodetection.In the experiment,we got clear and steady triangular waveform signals with repetition frequencies of 6GHz,5GHz,3GHz,respectively.The scheme not only keeps the advantages of photonic technology in generating triangular waveform signal,but also presents more simple configuration,better flexibility and performance.The second method is the triangular microwave waveform signal generation based on an OEO system,since OEO can be regarded as an better microwave source.In the scheme,under the tradition condition of OEO,without adding any active device,The polarization angle of the light beam is controlled and entered into the MZM with an angle for the best modulation axis by adjusted the polarization controller.According to the MZMs' characteristics,a part of the light field executed carrier suppression,and the orthogonal part is not modulated.After that the modulation of light field passing through a rectangular window filter,the negative order sidebands are fitted out.Finally,the two orthogonal optical fields are partly projected into the same direction by an polarizer,whose intensity are controllable by a PC before the polarizer.When all the optical conponents are beat on a PD,triangular microwave waveform can be generated.In the experiments,we got clear and steady triangular waveform signals with repetition frequencies of 5GHz,and the signal's suppression is high and the phase noise is good.Studying of microwave arbitrary waveform is very important,and it has distinct meaning of the generation and transmission of microwave signals through optical methods.