title: Oscillatory vertical coupling between a whispering-gallery resonator and a bus waveguide.
abstract: We report on a theoretical and experimental study of the optical coupling between a whispering-gallery type resonator and a waveguide lying on different planes. In contrast to the usual in-plane geometry, the present vertical one is characterized by an oscillatory behavior of the effective coupling as a function of the vertical gap. This behavior manifests itself as oscillations in both the resonance peak waveguide transmission and the mode quality factor. An analytical description based on coupled-mode theory and a two-port beam-splitter model of the waveguide-resonator vertical coupling is developed for arbitrary phase-matching conditions and is successfully used to interpret the experimental observations.
authors.affiliation: Advanced Photonics and Photovoltaics Unit, Fondazione Bruno Kessler, I-38123 Povo, Italy. ghulinyan@fbk.eu
authors.forename: M
authors.initials: M
authors.lastname: Ghulinyan
authors.forename: F
authors.initials: F
authors.lastname: Ramiro-Manzano
authors.forename: N
authors.initials: N
authors.lastname: Prtljaga
authors.forename: R
authors.initials: R
authors.lastname: Guider
authors.forename: I
authors.initials: I
authors.lastname: Carusotto
authors.forename: A
authors.initials: A
authors.lastname: Pitanti
authors.forename: G
authors.initials: G
authors.lastname: Pucker
authors.forename: L
authors.initials: L
authors.lastname: Pavesi