I am using the SiEPIC EBeam PDK:
I followed the layout driven approach introduced in this conference paper:
Since 3D FDTD simulation of ring resonators requires long simulation time, it is quite useful to model the ring resonator as 2 directional couplers connected to each other. In the paper above, the ports of the ring resonators are connected to grating couplers to couple the light in and out.
Instead of manually creating the layout as described above, an easier way is to use Python scripting in Klayout. This requires minimal effort since there’s a ready made Macro for this. After following the installation steps here, open Klayout and create a new layout. Click Macros>>Macro Development. On the left panel, double click on python script named “Layout_DoubleBus_RingResonator”. Basically, this script generates ring resonators of predetermined radii and gaps. To try this, I clicked on the green run button at the top. However, I wanted to study a ring resonator of 4 um radius and 50 nm gap. So, I changed this in the script as highlighted below.
To test the behavior of the circuit, I clicked on the INTERCONNECT icon in Klayout as in the video above.
INTERCONNECT opens and I got this message:
The drop list has 2 options either to choose the closest S-parameters or generate S-parameters. I noticed that this didn’t occur when I ran the circuit simulation for radii of 3 and 5 um. In these cases, I directly got the results shown below:
So, what do you think is the problem with the 4 um radius case?