Comparative Analysis of Optical Ring Resonators with Cross- and Direct-Coupled Configurations

This paper presents a proposed alternate configuration for optical ring resonator (ORR) having a resonance loop made of single-mode optical fiber. Under steady state condition, the responses of the proposed ORR are formulated by considering the output and loop intensities for various conditions of transmission coefficient, power coupling coefficient, and compared the results with the previous reported ORR configuration. The analyses have shown that the main difference between two ORRs is due to the values of power coupling coefficients of the couplers used in their configurations. Another major point, that is to be considered in design of ORR for a maximum output power is that the transmission coefficient and power coupling coefficient in the proposed configuration are not required to be equal, as the case of the previously reported configuration. The analytical results given in this article can be useful for selection of ORR configuration for particular applications, specially in case of nonlinear use of ORR configuration.