title: Ultra-high quality-factor resonators with perfect azimuthal modal-symmetry.
abstract: We study circular grating resonators (CGRs) which are formed by a central defect surrounded by concentric rings composing a grating and which display perfect azimuthal modal-symmetry. Because of their radial symmetry they exhibit a complete band gap for a minimal index contrast. However, as is the case for all 2D resonators their quality factors are limited by vertical losses. To reduce the vertical losses we introduce a chirp of the grating period by reducing it towards the central defect. The chirped CGRs exhibit drastically improved quality factors of up to tens of millions with a modal volume of a few cubic wavelengths.
authors.affiliation: IBM Research - Zurich, 8803 Rüschlikon, Switzerland. nim@zurich.ibm.com
authors.forename: Nikolaj
authors.initials: N
authors.lastname: Moll
authors.forename: Thilo
authors.initials: T
authors.lastname: Stöferle
authors.forename: Sophie
authors.initials: S
authors.lastname: Schönenberger
authors.forename: Rainer F
authors.initials: RF
authors.lastname: Mahrt
mesh_terms: D004581:Electronics; D004867:Equipment Design; D007834:Lasers; D055096:Optical Devices; D055095:Optics and Photonics; D011789:Quantum Theory; D012031:Refractometry / Q000295:instrumentation / Q000379:methods; D012815:Signal Processing, Computer-Assisted; D013053:Spectrophotometry / Q000295:instrumentation / Q000379:methods