title: Coupling-loss reduction of a vertically coupled microring resonator filter by spot-size-matched busline waveguides.
abstract: To improve the input-output coupling loss of a vertically coupled microring resonator filter, we fabricated microring resonators on an antiresonant reflecting optical waveguide (ARROW) with a large spot size and on the rectangular busline waveguide with a spot-size transformer. The spot size and the tapered structure were optimally designed from the viewpoint of spot-size matching to single-mode fibers and the reduction of radiation loss. Clear dropping responses were demonstrated for the ARROW-based microring resonator filters, and the coupling loss was successfully reduced by 22 dB.
authors.affiliation: Graduate School of Engineering, Yokohama National University, Japan.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Kato
authors.forename: Shuichi
authors.initials: S
authors.lastname: Suzuki
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Kokubun
authors.forename: Sai Tak
authors.initials: ST
authors.lastname: Chu