title: Experimental demonstration of waveguide-coupled round-cornered octagonal microresonators in silicon nitride.
abstract: We report laterally waveguide-coupled octagonal microresonators with designed round resonator corners in silicon nitride. We demonstrate nearly single-mode add-drop filter characteristics, when 50-microm-size round-cornered octagonal microresonators are used, with an optimum coupling efficiency exceeding 96%, a finesse of approximately 30, and a Q of approximately 6400. Our experiments also reveal two unforeseen phenomena in certain microresonator shapes: a pronounced drop in coupling efficiency and resonance notches in the drop spectrum. These device characteristics hint at the recently postulated multiple orbit interference in waveguide-coupled polygonal microresonators.
authors.affiliation: Department of Electrical and Electronic Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong Special Administrative Region, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Li
authors.forename: Andrew W
authors.initials: AW
authors.lastname: Poon