In this Letter, we report group index measurements of the supermodes of an array of two strongly coupled silicon-on-insulator waveguides. We observe coupling-induced dispersion that is greater than the material and waveguide dispersion of the individual waveguides. We demonstrate that the system transforms from supporting the two supermodes associated with two coupled waveguides to the single mode of a slot waveguide within the investigated spectral range. During the cutoff of the antisymmetric supermode, an anti-crossing between the symmetric TM and antisymmetric TE supermodes has been observed.
© 2010 Optical Society of America
Original Manuscript: June 3, 2010
Revised Manuscript: October 15, 2010
Manuscript Accepted: October 22, 2010
Published: November 22, 2010
Charles E. de Nobriga, Gareth D. Hobbs, William J. Wadsworth, Jonathan C. Knight, Dmitry V. Skryabin, Antonio Samarelli, Marc Sorel, and Richard M. De La Rue, "Supermode dispersion and waveguide-to-slot mode transition in arrays of silicon-on-insulator waveguides," Opt. Lett. 35, 3925-3927 (2010)