Research On Microwave Photonic Filter Based On HBF Sagnac Ring

With the development of information technologies, the demands of transmissionrate and bandwidtli for all kinds of transmission systems have increased dramatically.Optical ifber communication technology shows a lot of advantages in the aspects ofhigh speed, large capacity, high bandwidth information transmission, which gets wideattentions and have a lof of applications. With the development of WDM technology，especially DWDM technology, which makes full use of the frequency band of opticalfiber. Thus, it has become an effective technical means for the upgrading andexpansion of the communication system.In the last ten years, the microwave photonic iflters, which as one of the keydevice in ROF system, have become the focuses of current research. In particular,introducing the HBF into the Sagnac loop constitutes microwave photonic iflter, ithave gotten great attentions because of simple structure, polarization independent,high side mode suppression ratio and easy tuning, etc. In addition, microwavephotonic filter based on HiBi-PCF Sagnac loop has the characteristics such as highbirefirngence and insensitivity to temperature, which can realize the microwavephotonic iflter of high channel isolation degree and insensitivity to temperaturechanges.In this thesis, we mainly study on microwave photonic filter based on HBFSagnac loop. The main works and innovations are as follows:1.Analyzing and comparing the domestic and overseas research status of vairetyof optical filters and the microwave photonic filters based on fiber Sagnac loop, theresult embodies that the microwave photonic filter based on HBF Sagnac loop havethe larger advantage and application potential.2.Study on the basic principle of the one-order IIBF Sagnac loop microwavephotonic filter, Matlab simulating the output spectra of the filter. Deep analyzing thedevices parameters of the filter which have influence to the output spectra andoptimizing devices parameters.3.Study on the high-order HBF Sagnac loop microwave photonic filter. establishing theoretical models by using transfer matrix, deriving the transferfunction of two-order, three-order HBF Solc-Sagnac loop filter and two-order HBFLyot-Sagnac loop iflter. And then, analyzing the output spectra of higher-order HBFSagnac loop microwave photonic iflter with different devices parameters. Theresults show that the filteirng spectra of high-order HBF Sagnac loop microwavephotonic filter have the characteristics of diversity and fine, which can meet thedemands of different filteirng scenarios.4.Study on tunable filter theory of microwave photonic filters based on HBFSagnac loop，a kind of tunable microwave photonic iflter based on HBF Sagnac loopand cantilever tuning unit based on electromagnetic force is designed, theoreticalresearch and Matlab simulation are conducted to this filter, which obtains themicrowave photonic filter of all-fiber structure and center wavelength tunable.5.Based on the above studies, in order to obtain the microwave photonic filter ofhigh channel isolation and insensitivity to the temperature change, a Sagnac loopcascade filter based on HiBi-PCF is designed, theoretical research and Matlabsimulation are conducted to this iflter.The filter’s FWHM is0.4run, which can beapplied to the50GHz DWDM systems.