Ring Resonator-Based Broadband Photonic Beam Former for Phased Array Antennas

This thesis presents the principles and a demonstration of optical ring resonator (ORR)-based broadband photonic beam former for phased array antennas. In Chapter 1 an introduction of RF photonics is given. The SMART and BPB projects are summarized, which are aimed for the development of ORR-based broadband photonic beam former for phased array antennas. In the SMART project the antenna is used for the aeronautic communication of Ku-band signals; in the BPB project the antenna is part of a radio telescope which is used for astronomical research. In Chapter 1 the principles of phased array antennas and optical beam forming are also explained. In Chapter 2 the principles of using a single and cascaded ORRs as delay elements are described. The ORRs are studied by means of their mathematical models. Moreover, a formula is derived to calculate the necessary number of ORRs for a desired delay response, which is useful for the design of the ORR-based optical beam forming networks (OBFNs). Basically an OBFN consists of delay elements (DEs) and combining circuitry. In this thesis only the single-wavelength schemes for the OBFN are discussed where coherent optical combining is required. In Chapter 3 different OBFN architectures are compared with respect to the system complexity and feasibility. It appears that the asymmetrical binary-tree structured OBFN results in the lowest system complexity compared to its counterparts, and it can be used for both linear (1-dimensional) and planar (2-dimentional) PAAs. In Chapter 4 different schemes for E/O and O/E conversions of the photonic beam former are compared with respect to optical bandwidth efficiency and system complexity. Finally, a practical architecture for the entire beam former system is found, which includes frequency down-conversion (FDC), optical sideband filter (OSBF)-based single sideband-suppressed carrier (SSB-SC) modulation, optical carrier reinsertion and balanced coherent optical detection. The FDC significantly relaxes the bandwidth requirements on the optical modulators; the SSB-SC modulation relaxes the bandwidth requirements on the OBFN and detectors; the use of coherent optical detection enhances the signal dynamic range of the beam former. Based on this practical architecture, the functional modules of beam former systems for the FLY and SKY project are designed. Then in Chapter 5 the realization processes of the FLY and SKY beam former chips are described. The beam former chip includes OBFN, OSBF, and the optical carrier reinsertion coupler. Low fabrication cost and simple implementation are achieved, since the waveguide fabrication is based on …