A new class of optical components based on directional coupler resonators (DCRs) is proposed. A DCR has three basic components: a directional coupler, mirrors attached to, or built into, the waveguides or fibers, and a mechanism to vary the optical length of waveguides or fibers. The characteristics of DCRs have been analyzed. It is shown that the transmission and reflection responses of DCRs can be varied drastically by changing the lengths of the waveguide or fiber attached to the coupler. Making use of this feature, simple optical components can be realized. Five specific applications of DCR components are discussed. For DCR components, the perturbations or changes occur entirely outside the coupler interaction region. Thus DCRs are basically different from the usual directional coupler devices where the perturbation is confined entirely inside the interaction region.
© 1987 Optical Society of America
Chin-Lin Chen, "Directional coupler resonators as guided-wave optical components: a proposal," Appl. Opt. 26, 2612-2617 (1987)