Optical filter having multiple interferometric stages.

摘要

The filter includes a substrate having a longitudinal axis and first and second optical waveguides formed on the substrate. The waveguides have respective first and second effective refractive indices. The filter is subdivided into N stages, when N is at least 2, and N + 1 approximately equally spaced-apart coupling sections, such that each stage is situated between two coupling sections. The first waveguide is optically coupled to the second waveguide in each of the coupling sections. The optical path length within each stage is greater int he first waveguide than in the second waveguide. The first and second effective refractive indices are nominally equal.