Learning Forum

[jasper]

Hi,

I am trying to simulate a Distributed Bragg Reflector that is optimized for maximum reflectance at 1550nm. I have checked the simulation geometry and it seems to be correct, so I am wondering about other causes of such a low reflectance. (It should be around 1.) Are there any simulation settings that I might have overlooked, causing this behaviour?

Please let me know if you need more input.

Thanks in advance!

 

[Amrita Pati]

Hi Jasper,

What type of source are you using?

Regards,
Amrita

[jasper]

Hi,

I am using the fundamental TE Modes from the EME port as my source. I have also tried using the fundamental TM Mode and both, but all give too low reflectivity. The DBR is designed to only carry the fundamental TE and TM modes.

[jasper]

I have also noticed that the mode convergence sweep doesn't converge (when using conserve energy): 

Interestingly, here (“CVCS” or “none” for the taper waveguide coupler (ansys.com)) it is recommended to make energy conservation passive, whereas here (EME solver - Simulation object – Ansys Optics) it is mentioned that energy conservation should be enabled when simulating a periodic structure. So which option should I use? 

Best regards, 

Jasper

[Amrita Pati]

Hi Jasper,

CVCS is used for structures whose transverse cross-sections vary continuously like a taper. Would you be able to share screenshots of your geometry and the EME setup tab? Like you mentioned, since it is a periodic structure I would suggest you to keep the energy conservation option as "conserve energy".

Regards,
Amrita

[jasper]

Sure! This is the geometry:

The Grating is divided in two sections, one of which is a normal waveguide and the other has two posts next two it. This is the setup tab:

I have also selected the "force symmetric y mesh" option. 

[jasper]

Got it fixed after using custom eigensolver settings: For cell 1 (The single mode waveguide section), only use 2 modes.