I was reading the tutorial of Traveling wave modulator, and would like to simulate a waveguide modulator similar to the one on tutorial. There was a section talking about how to simulate Rslab. Here I have one question about the unit. The simulation was a 2D Y-normal simulation. But the results were extracted from the current and voltage. I wonder why a 2D simulation can give the current. Also, I found that the simulated resistance (1.8 ohm) was smaller than the values (10-15 ohm-mm, unit different again) I read on the papers. Finally, there should be contact resistance between Al and silicon. Therefore, I would like to know how to simulate this series resistance well.