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Sub-wavelength grating gradient index mode transformers in high index contrast slab waveguidesFormat | Member Price | Non-Member Price |
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Paper Abstract
We report on new types of sub-wavelength grating gradient index structures for efficient mode coupling in high index
contrast slab waveguides. Using sub-wavelength gratings (SWGs), an adiabatic transition can be formed at the interface
between slab waveguides of different core thicknesses. The SWG transition region minimizes both mode mismatch loss
and coupling to higher order modes. By creating the adiabatic gradient effective index region in the direction of
propagation, we demonstrate that vertical mode size transformation is readily achieved in structures that can be
fabricated using a single etch step. Using 3D finite-difference time-domain simulations we study the loss, polarization
dependence and the higher order mode excitation for two types (triangular and triangular-transverse) of SWG transition
regions between silicon-on-insulator slab waveguides of different core thicknesses. We also demonstrate two solutions to
mitigate polarization dependent loss, namely using a partial transverse SWG and a SWG in the region between the
triangular teeth. Our mode transformer designs are optimized for applications in polarization compensator in echelle
grating and arrayed waveguide grating (AWG) multiplexers and a gradient index interface between the ridge waveguide
and the slab combiner region in a curved waveguide grating demultiplexer.
Paper Details
Date Published: 18 February 2009
PDF: 7 pages
Proc. SPIE 7220, Silicon Photonics IV, 722005 (18 February 2009); doi: 10.1117/12.809736
Published in SPIE Proceedings Vol. 7220:
Silicon Photonics IV
Joel A. Kubby; Graham T. Reed, Editor(s)
PDF: 7 pages
Proc. SPIE 7220, Silicon Photonics IV, 722005 (18 February 2009); doi: 10.1117/12.809736
Show Author Affiliations
P. J. Bock, Univ. of Ottawa (Canada)
National Research Council Canada (Canada)
P. Cheben, National Research Council Canada (Canada)
J. H. Schmid, National Research Council Canada (Canada)
National Research Council Canada (Canada)
P. Cheben, National Research Council Canada (Canada)
J. H. Schmid, National Research Council Canada (Canada)
D.-X. Xu, National Research Council Canada (Canada)
S. Janz, National Research Council Canada (Canada)
T. J. Hall, Univ. of Ottawa (Canada)
S. Janz, National Research Council Canada (Canada)
T. J. Hall, Univ. of Ottawa (Canada)
Published in SPIE Proceedings Vol. 7220:
Silicon Photonics IV
Joel A. Kubby; Graham T. Reed, Editor(s)
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