Learning Forum

[Mounika Chinthakindi]

I'm doing simulation in FDTD and using gaussian source and plane wave source at the same time. am I allowed to do so?
Also, what are the units for the transmission and power results from the monitor? 

[Guilin Sun]

if you provide mode details such as device configuration and results you want, maybe I can give you more suggestions.

In theory, you can use more than one source. However please note that they will be coherent. 

If they have different bandspectrum, you may only get accurate result without normalization, or use time domain signal.

If it is nonlinear, you can use two or more sources, please refer to https://optics.ansys.com/hc/en-us/articles/360042192953-Pump-probe-simulation-using-4-level-2-electron-material

Transmission is the ratio of transmitted power over injection power, so it is unitless.

Power will be in Watt.

[Mounika Chinthakindi]

My device is slotted waveguide based THz modulator where I will be using GermaniumSelenide as 2D material in the slot of the signal line which has light sensitive conductivity. For light source I'm using Gassian sourcem of wavelegth 300nm to 1000nm with varying amplitude. With incidence light its conductivity changes by which modulation happens. I also need to pass a THz signal through the signal line, for that I'm using Plane wave source of Frequency  60GHz and 220GHz. I need to see change in conductivity in GeSe but it is not changing for what ever wavelength of the light.  

[Guilin Sun]

Currently no optics/electric cosimulation is available. Simply injecting GHz wave will not induce any change of the refractive index or conductivity (photoconductivity), since the material model does not have such behavior. What you need is to calculate the absoption which is used to calculate the change of conductivity, and use the change to modify the material data for optic simulation.

Directly simulation with electronic simulation like CHARGE will need to set the material to be semiconductor. I am not sure if this works for you.

In summary, you will need to find a way to get the photoconductivity change by the THz exciation, and then using FDTD to do the optic simulation. As for what tool you will need for the photoconductivity, it is an open question.