Poonam,
The design you have included has no observation areas, are you certain that is the design you are using to get those results? Because I am unable to duplicate your field data. I do note a couple of things:
- Why is your injected field 1.414 um when that waveguide is only about 0.6 um? This gives very poor overlap between the waveguide mode and your field which means much of the field will be dumped into the crystal where it cannot propagate.
- Why is your source inside the crystal? If you inject from outside the crystal you either get power in the waveguide or it does not enter at all.
- You seem to have both 2D and 3D simulation parameters set, which simulation are those results from?
- You are using the default resolution (lambda/10) which is in my opinion too coarse for your structure with a source of 1.55 um. Have you done any convergence testing?
- Finally I moved the input plane outside the crystal and changed the DFT specifications to be from 0.8 um to 3 um. What I observed from the observation area that there is couple into the waveguide from about 0.8 um up to about 1.4 um. It is my assessment that the waveguide in question does not support modes with wavelengths beyond about 1.4 um as it is too narrow.
Scott