phase of transmission

mode
fdtd
transmission
sparameter

#1

hello
i want to calculate the phase of transmission in mode solver VarFDTD by using sparameter .
the abs^2 transmission that achieved with sparameter differ from transmission directly achieved with freq monitor?
how can i solve this problem?
i appreciate in advanced who can help me as soon as possible.
the scription for sparameter is attacheduntitled.lsf (286 Bytes)
thanks.


#2

Hi @h_taleb
I would like to give me more details about your issue. I would recommend you to read carefully the example about ring resonator and learn how to extract the S parameters. https://kb.lumerical.com/en/index.html?pic_passive_getting_started.html
You said that:
"It is expected that the abs^2 transmission that achieved with sparameter differ from transmission directly achieved with frequency domain field and power monitor"
But in the script i can see that you have "Abs(S21)

Also, i have to mention that it is expected the result from the frequency field and power monitor to be different from the script. Please read carefully the example about the ring resonator and how to extract the S parameters.

Best regards!


#3

hi
the transmission achieved with the output freq monitor is attached:
and the transmission from scription that attached in previous message is:

as seen in the above two plot is completely different and i don’t know what is the problem?
best regard


#4

Dear @h_taleb

It looks like your plots match except the values in y-axis, maybe we are off by a normalization factor? Can you please upload your simulation file and scripts for a review.

Thanks


#5

Dear bkhanaliloo
thank you for your response i appreciate you in advance if you solve my problem.untitled.lsf (286 Bytes)
forward 3x power - Copy.lms (1.7 MB)


#6

Hi @h_taleb

I guess you didn’t define S21 properly. Since you want to measure light that passes through two monitors (light in the x-direction) it should be:
S21=out.a/in.a.

I hope this answers the question.

p.s.: Can you explain what is the geometry, specifically the role of the hole in the waveguide section?

Thanks


#7

Hi
thank you for your response it is right.
the structure is an assymetric light transmission and block hole in the waveguide break symmetric in the structre.
Best Regard.