Time Delay And Filtering Properties Of Waveguide Microring Resonator

Microwave photonic technology in microwave signal generation, transmission and processing area has tremendous potential application prospects, especially in optical controlled phased-array antenna (OCPA) system. Using optical delay line based on microwave photonic technology, which has large instantaneous bandwidth, can avoid beam "squint" phenomenon caused by electrical phase shifter, and achieve precise beam scanning and control. With radio over fiber (RoF) technology the RF signal received from antenna array can be transimitted to the central station through a long distance with low loss and good immunity to electromagnetic interference (EMI). The new generation of OCPA with high-performance, high integration will utilize the integrated waveguide optical delay line based on photonic integration technology. Ultimately to achieve the monolithic integration of the laser, electro-optic modulators, optical switches, optical delay lines, optical filters and photo detectors et al. Thus to realize smaller size, lower power, and to improve system stability, which are very important for the phased array antenna system in the spaceborne and airborne. The purpose of this thesis is to study the optical delay and microwave photonic filtering properties of waveguide microring resonator.Through the analysis of frequency response characteristics of the microring, the influencing factors, such as coupling coefficients, round trip loss and round trip delay time, and their mechanism for the delay characteristics of optical microring have been investigated. The effect of the coupling conditions on the time delay flat properties of cascaded waveguide ring resonators has also been studied. The rusults provide a good theoretical basis for the design and application of the optical delay line based on microring in future. Through the study on the time domain characteristics of waveguide microring resonator, the influence of time delay parameters, such as time-delay bandwidth, time-delay ripples and waveguide loss, on the pulse signal transmission properties, for example response time, pulse shape, and pulse amplitude, has been analyzed, which provides a good reference for the signal processing application in future.The Mach-Zehnder Interferometer (MZI) is proposed to replace the conventional waveguide directional coupler in the ring, which can achieve the continuous tuning of delay time combining with the phase shifter on the ring waveguide. The impact of additional phase brought by MZI on the ring is also analyzed. In the end, the mask of optical delay line based on MZI-ring with bandwidth of 3GHz and tunable time delay range of 0-346.4ps is designed.Microwave photonics filtering properties of intergrated waveguide microring resonator based on polymer PSQ is investigated through some experiments. Its notch filtering characteristic at the resonant frequency is used to overcome the fading effect in the double sideband (DSB) modulated RoF system, which is introduced by the optical fiber chromatic dispersion. Part of one side-band of DSB is suppressed when it is just at the resonant frequency of microring.20Mbps QPSK signal carried by 14.35 GHz microwave is transmitted successfully over 25 km single mode fiber (SMF) in the experiment.