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.
© 2009 Optical Society of America
OCIS codes: (130.0130) Integrated optics; (230.5750) Resonators
Keywords: Stoferle, Stoeferle, Schonenberger, Schoenenberger
By: N. Moll, T. Stöferle, S. Schönenberger, R.F. Mahrt
Published in: Optics Express, volume 17, (no 23), pages 20998 in 2009
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