Patent ID: 6865317

Claim:
A resonant optical filter for an optical WDM system, comprising: a first transmission fiber-optic waveguide, the waveguide having a fiber-optic-taper segment therein; a second transmission fiber-optic waveguide, the second waveguide having a fiber-optic-taper segment therein; and a resonator fiber having at least one fiber-ring resonator segment formed thereon, each fiber-ring resonator being evanescently optically coupled together and thereby acting as a single fiber-ring resonator, wherein: the resonator fiber further includes a taper positioner for engaging the fiber-optic-taper segment of at least one of the transmission fiber optic waveguides so as to reproducibly establish and stably maintain an evanescent optical coupling of the fiber-ring resonator and at least one of the transmission fiber optic waveguides; the fiber optic taper segment of at least one of the transmission fiber optic waveguides is partially wrapped around a portion of an outer circumference of at least one fiber-ring resonator segment; the resonator fiber includes a delocalized-optical-mode suppressor; and the resonant frequencies of the fiber-ring resonator segment have been modified by beam processing.