Integrated optical filters using Bragg gratings and resonators

Abstract

This thesis provides an in-depth study of optical filters made using integrated Bragg gratings and Bragg resonators. Various topologies for making add/drop filters using integrated gratings are outlined. Each class of devices is studied in detail and the theoretical tools needed for designing the add/drop are developed. First-order filters using Bragg resonators do not meet WDM add/drop filter specifications. Consequently, schemes to design higher-order filters are derived. The relative advantages and disadvantages of the various possiblities are outlined. Preliminary integrated Bragg grating devices, in InP, were designed using the tools developed. The fabricated devices were measured. The measurements revealed low-loss structures with a < 0.1 cm-l and high-Q Bragg resonators with Q > 40, 000. Measurements on higher-order inline coupled Bragg resonator filters showed flat-top and fast roll-offs. The results of the measurements and comparison with the theory are presented for the various devices. The results reveal that Bragg grating based devices offer tremendous potential for use as add/drop filters in WDM systems.