Optical fiber filter comprising a single-coupler fiber ring (or loop) and a double-coupler fiber mirror

A theoretical study of an optical fiber filter comprising a double-coupler fiber loop mirror and a single-coupler fiber ring (or loop) is presented. An active scheme using degenerate two-wave mixing is also proposed. The circulating, transmitted and reflected output fields and intensities, as well as some performance parameters such as the peak transmission, contrast and contrasted transmission, are computed and presented in graphical form. The characteristics and potential applications of this filter are discussed. It is found that the use of degenerate two-wave mixing results in a significant increase in the finesse and a dramatic change in the output characteristics of the filter