Research on optically integrated directional coupler-modulators and electrooptic oscillators

An electrooptic modulator with one band filter in a feedback coupling network is investigated. The manufacture of an optically integrated lithium niobate waveguide is considered. The crystal structure and mechanical, electrical, and optical characteristics of lithium niobate are reviewed and the technology used to produce a titanium-diffusion-doped strip waveguide is discussed. An electrically steerable optical directional coupler (DC) is studied in detail, including the field theory and steering characteristics of dielectric DCs, the optical characteristics of optical DCs, the modulation characteristics of steerable DCs, and the DC steering electrodes. The basic switching in electrooptic feedback coupling systems is considered for both bistable and astable systems. Theoretical and experimental results on electrooptic oscillators are presented, and the synchronization of amplitude-modulated optical signals is discussed.