Learning Forum

[Jordi Lopez Leyva]

I want to do a simulation with FDTD and CHARGE modules combined. Is that possible?

Specifically, have a cavity where light generates carriers, which should diffuse to dark regions. This would alter the refractive index and change cavity resonance and thus change carrier generation at the next time step. So I want to do FDTD->CHARGE->FDTD->etc x 10000. Is such as simulation possible with Lumerical, or is COMSOL recommended for this?

[Amrita Pati]

Hi Jordi,

I don't think we have any exisiting examples that go back and forth between CHARGE and FDTD. If you have something like a photodiode, then you do the simulation first in FDTD to simulate the absorption of light, then you import this to CHARGE to calculate the photocurrent under bias. If you have a modulator, then you calculate the charge injection first in CHARGE. Then the index perturbation due to either of these is calculated to determine other modal properties like effective index, losses etc.

So, I think this can also be done in Lumerical, this is more like a two-way simulation. Here are the links to the examples on:

1. Vertical photodetector
2.  PIN Mach-Zehnder modulator

Let me know if you have any questions.

Regards,
Amrita

[Jordi Lopez Leyva]

Hi Amrita,

Thank you. I want to simulate the photorefractive effect, which uses photoconductivity. Is it possible to simulate traps? So light will excite carriers from traps, these will diffuse due to high carrier density to low densities where there's less light, and relax towards another trap. 

I understand Lumerical can do Shockley Read Hall recombinations and Auger, but I want to observe the trapping of space charge. Would this be possible in Lumerical?

[Amrita Pati]

Hi Jordi,

Would you be able to share a reference on this? Thank you!

Regards,
Amrita

[Jordi Lopez Leyva]

Hi Amrita,

This paper describes an implementation of FDTD in a bulk phototrefractive crystal. A key difference from my implementation is I only use 1 light pulse (instead of 2), and want to generate the photorefractive patterns in the photonic crystal due to the self interference of the photonic crystal.

(Laporte, Floris, Joni Dambre, and Peter Bienstman. "Simulating self-learning in photorefractive optical reservoir computers." Scientific Reports 11.1 (2021): 2701.)