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Proceedings Paper

Analysis of couplers between photonic nanowires and subwavelength grating waveguides
Author(s): Jirí Ctyroký; Pavel Kwiecien; Ivan Richter; Pavel Cheben
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Paper Abstract

Subwavelength grating (SWG) waveguides offer the freedom of (effective) refractive index variation in the design of integrated optical components and devices in silicon-on-insulator waveguides without significantly increasing fabrication complexity. An SWG waveguide is formed by a subwavelength (quasi)-periodic structure consisting of short segments of silicon embedded into a lower-index superstrate. As a result, to the first approximation, the SWG waveguide behaves as a channel waveguide with its core refractive index determined by the filling factor of silicon in the superstrate. By changing the filling factor, i.e., the duty-cycle of the SWG structure, its (effective) refractive index can be varied essentially between that of the superstrate and that of silicon. Here we present a numerical analysis of light coupling between a conventional silicon nanowire waveguide and a periodic SWG waveguide by means of a tapered SWG coupler. The coupler function is to facilitate the smooth and low-loss transition from a conventional mode of a photonic nanowire to a Bloch mode of a periodic SWG waveguide, both propagating with different group velocities. To increase the reliability of numerical simulations, two independent 3D numerical codes based on different formulations of a Fourier modal method (FMM) are used for the analysis. Results of modeling of tapered SWG couplers of different lengths confirm excellent optical properties of these couplers, including very low coupling and return losses.

Paper Details

Date Published: 21 May 2013
PDF: 8 pages
Proc. SPIE 8781, Integrated Optics: Physics and Simulations, 87810B (21 May 2013); doi: 10.1117/12.2017077
Show Author Affiliations
Jirí Ctyroký, Institute of Photonics and Electronics of the ASCR, v.v.i. (Czech Republic)
Pavel Kwiecien, Czech Technical Univ. in Prague (Czech Republic)
Ivan Richter, Czech Technical Univ. in Prague (Czech Republic)
Pavel Cheben, National Research Council Canada (Canada)

Published in SPIE Proceedings Vol. 8781:
Integrated Optics: Physics and Simulations
Pavel Cheben; Jiří Čtyroký; Iñigo Molina-Fernandez, Editor(s)

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