Figure 2
Effect of the strip width on the coupling length for configurations with and without the silicon strip array (SA). The widths of the silicon ridge waveguides are selected as 500 nm to ensure the existence of strongly confined TE modes. (a) A single strip; (b) two strips; (c) three strips; (d) four strips. Geometric parameters for the silicon waveguide pair are w = 500 nm, h = 220 nm, S = 500 nm. Ex field distributions of the symmetric and anti-symmetric super-TE-modes in the optimal coupling systems with the largest coupling length are plotted as well. The widths of the strip(s) corresponding to the optimal coupling lengths are w s = 120 nm for a single strip (a), w s = 126 nm for two strips (b), w s = 76 nm for three strips (c) and w s = 48 nm for four strips (d).
