Open AccessThe longitudinal offset technique for apodization of coupled resonator optical waveguide devices: concept and fabrication tolerance analysis
Author(s) -
José David Doménech,
Pascual Muñoz,
J. Capmany
Publication year - 2009
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.17.021050
Subject(s) - resonator , apodization , optics , fabrication , offset (computer science) , coupling coefficient of resonators , materials science , waveguide , coupled mode theory , refractive index , physics , computer science , medicine , alternative medicine , pathology , programming language
In this paper, a novel technique to set the coupling constant between cells of a coupled resonator optical waveguide (CROW) device, in order to tailor the filter response, is presented. The technique is demonstrated by simulation assuming a racetrack ring resonator geometry. It consists on changing the effective length of the coupling section by applying a longitudinal offset between the resonators. On the contrary, the conventional techniques are based in the transversal change of the distance between the ring resonators, in steps that are commonly below the current fabrication resolution step (nm scale), leading to strong restrictions in the designs. The proposed longitudinal offset technique allows a more precise control of the coupling and presents an increased robustness against the fabrication limitations, since the needed resolution step is two orders of magnitude higher. Both techniques are compared in terms of the transmission esponse of CROW devices, under finite fabrication resolution steps.