The following images depict the first stages of a waveguide photodetector design in Rsoft., The input waveguide is 2 microns, followed by a tapered section to a 10 micron wide photodetector region. Three tapering typologies are used. Following these initial simulations come optimization of the photodetector region and electrical simulations.
First, the layer view. This section is at the input waveguide.
The InGaAs layers above the waveguide serve to absorb the optical power in the photodetector region:
Three different input tapers are used:
Absorption in the photodetector region is in the range of 95%.
Here is the optical power remaining in the waveguide region: