Blue-shifted contra-directional coupling between a periodic and conventional dielectric waveguides.
The interaction between a periodic and conventional dielectric waveguides is investigated theoretically for a two-dimensional model system. A modified coupled-mode theory is formulated for the considered system and found to agree well with rigorous numerical calculations. It is shown that in a certain wavelength range the contra-directional coupling between the two waveguides can be achieved with high efficiency. But the spectrum of the coupling efficiency is blue-shifted and thus the strongest coupling does not occur in the case when two individual waveguides have the same propagation constant. For such a contra-directional coupling system, the coupling efficiency grows with the coupling length and it tends to 100% (excluding insertion loss) when the coupling length is larger than a certain value, and the coupling window can be largely broaden by reducing the distance between the coupled waveguides.
Shen
Linfang
L
Department of Information Science and Electronic Engineering, Zhejiang University, Zhejiang Province, Hangzhou 310027, PRC, China.
Chen
Xudong
X
Zhang
Xufeng
X
Pan
Li
L