Learning Forum

[filmartinelli]

Hello,

I am running a very basic simulation of transmission and reflection of a DBR structure in FDTD. The simulation is 3D and I have added two ports and the two extremes of the DBR. Attached picture of the geometry.

 

 

After running the simulation, I have opened the S parameter from port 1 (the one used to excite). To my understanding, this should represent the reflection of the structure. I have also checked the T parameter in the same port. Since this represent the light transmitted through this port and this is also the exication port, my understanding is that this value represents the reflection of the structure as well. 
However, the results are completely different and I cannot make sense of them. I believe I am not interpreting correctly the meaning of T but I cannot find any documentation that better explain it. I would be grateful if someone could help to clarify this point

Attached also S and T from port 1.

[GWANG]

Hi filmartinelli,

 

Thank you for the post. Which port is port 1 in your structure? Please note the light propagation direction for the port, and the transmission is the light going trough the ort along the light propagation; on the other hand the s-parameter defined for different input output combinations, for this structure I belice it contains S11. S21, S12 and S22. The two curves look to be exactly the opposite for me so please double check on the definition of the s-aprameter.