Study On Integrated Waveguide Microwave Photonic Filters Based On Microring

Microwave photonic technology takes the advantages of photonic technologies into microwave systems that transports and processes microwave signal with beneficial characteristics such as low loss, wide bandwidth, tunable etc. The development direction of microwave photonics technology is taking use of the advanced photonic integrated technology that integrates laser, modulator, microwave photonic filter, photodetector and other functional devices on the same chip, and then integrated with electronic devices, realizing that the system is small size, light weight and low power consumption at last. In this thesis, we study on filtering unit in integrated microwave photonic system, and we also analyze the characteristics, design the structure and research the filtering applications of microwave photonic filter which is based on integrated waveguide microring and combines integrated waveguide microring with Mach-Zehnder interferometer (MZI).In this paper, we firstly analyze the theory of filtering response characteristics of all-pass waveguide microring, test and analyze the filtering characteristics of polymer waveguide microring with directional coupler structure and polymer waveguide microring with tunable coupler structure respectively which are prepared by our own laboratory and get a good notch filtering function (Extinction ratio of12.3dB and18dB respectively). Then, the characteristic of high extinction ratio (ER) of the tunable microring is applied in the radio-over-fiber (RoF) system, realizing single sideband (SSB) filtering output in the experiment, solving the problem of power attenuation of microwave which is resulted from fiber dispersion by traditional double sideband (DSB) RoF system.Then, a new tunable microwave photonic filter combining ring resonator and MZI is proposed to realize filtering applications with high squareness, high ER and tunable. The influence of the filter structural parameters, such as coupling coefficient κr round-trip loss Υ1, and additional phase shift Δ(?), etc, on the filtering response are investigated. The simulation result shows that there is a tradeoff between the shape factor and ER. According to the polymer PSQ-L waveguide, a RF single sideband filter with shape factor of0.85and ER of32dB is designed, and the frequency tunability from8GHz to69GHz can be achieved with the thermal-optical phase shifters. Finally, a new single bandpass filter combining four ring resonators and MZI is proposed to realize reconfigurable filtering applications. Utilize the analysis method of digital filter to optimize and design its structural parameters, and its tunabilities (including the center wavelength tuning and bandwidth tuning) are analyzed. The simulation results show that there is a consistency between the shape factor and bandwidth but a tradeoff between flatness and bandwidth. Comparing the performance parameters of MZI+4Ring filter with those of multiple-ring-resonator filter, we conclude that the shape factor of MZI+4Ring is higher than that of multiple-ring-resonator, what’s more, through tuning the additional phases of microring, we can easily achieve the tuning of center wavelength and bandwidth at the same time. Therefore, MZI+4Ring has a stronger application prospects.