Photonics

Photonics

Topics related to Lumerical and more.

How to measure transmission coefficients on a given plane .

    • uzmayaqoob1960
      Subscriber

      In the attached picture i am interested to find |tx|^2 and |ty|2 from the simulated results attached below .The very first top right image is when x-pol is shine then directly observing monitor with any selection of X and Y components we got this image.When we choose selection operator X then we got bottom right image .But i am interested to find coefficients tx or ty or transmittance of x |tx|^2 and |ty|^2 components  as i ahve mentioned in the attachment(Fig1).So i run the following script for the selected monitor.

      1. x135xy=getdata("monitor_4100","x");

      2. y135xy=getdata("monitor_4100","y");

      3.E135xy=getelectric("monitor_4100");

      4.Ex135xy=getdata("monitor_4100","Ex");

      5.Ey135xy=getdata("monitor_4100","Ey");

      6.Ez135xy=getdata("monitor_4100","Ez");

      7.Hy135xy=getdata("monitor_4100","Hy");

      8.Pxxx=Ex135xy*conj(Hy135xy);

      9.M_powerx = 0.5*integrate(real(Pxxx),1:2,x135xy,y135xy);

      10.f=3e8/1550e-9;

      11.P=sourcepower(f);

      12.TXX=M_powerx/P;%|tx|^2

      13.Pyyy=-1*Ey135xy*conj(Ex135xy);

      14.M_powery = 0.5*integrate(real(Pyyy),1:2,x135xy,y135xy);

      15.Tyy=M_powery/P;  %|ty|^2

      Plz let me is line 12 and line 15 of the script are providing transmittance |tx|^2 and |ty|^2 or just tx and ty.When i run the code i got following values 

       

       

    • Dev
      Ansys Employee

      Hello, 

      Thanks for using ALF. Can you elaborate what device are you simulating? 

      Thank you. 

       

    • uzmayaqoob1960
      Subscriber

      Mam its a metasurface.That is producing high intensity spot for the provided input.Metasurface consist of 6 regions meansits a kind of 2X3 lens array where each lens is sensitive to a specific polarization (sect 1 (bottom left)is for x-polrzied light,sect2 (bottom right for y-polarized light) ,sect 3(middle left for 45 degree polarized light),sec4(middle right for 135 degree polarized light) ,sec5 (is for RCP light),sec6 is for LCP light.Mam i found this answer of Gulin sir as mentioned in this linkhttps://innovationspace.ansys.com/forum/forums/topic/how-to-calculate-the-transmission-of-a-particular-polarized-tranmission-2/

       but i am unable to find values of RCP and LCP transmission as he suggested can you plz guide in this regard as they asked to decompose .How could we use poynting vector as he did for x and y polarized light.Plz mam help me in this regard

    • anna.wirth-singh
      Ansys Employee

      Hi, 

      Thanks for providing some clarification on your quesiton. In the paper you shared, it looks like Tx and Ty are the transmission coefficients for x-polarized and y-polarized components. From the script, it seems that you are trying to run one simulation and decompose the results into components to get the results for both polarizations; is that right?

      I'd like to suggest, alternatively, would it be easier to run two different simulations (one for each polarization) to get Tx and Ty? You could try:

      1. Set the source to be polarized along X (polarization angle = 0) and run the simulation
      2. Get the Tx result using Tx = getdata("monitor_4100", "T"); and save that variable to the workspace
      3. Switch the source to polarization angle = 90 and run the simulation again
      4. Get Tx using Ty = getdata("monitor_4100", "T"); and save that variable to the workspace as well. 

       

      I would like to add that another way to integrate the amount of power through a particular plane would be to define a monitor where you want to measure, and then just get the "power" result from that monitor. 

    • uzmayaqoob1960
      Subscriber

      Dear Miss i am now opting integration method and switching source polarization at input side but as we are getting multiple spots out of which i want to see the intensity og highest intensity spot let say corresponding to x polarization input and 5 low intensity spots corresponding to 45 degree polarized light x,135 degree polarized light ,RCP and LCP.Thats Why sir i am using the same method Whuch Guilin sir suggested in this 

      https://innovationspace.ansys.com/forum/forums/topic/how-to-calculate-the-transmission-of-a-particular-polarized-tranmission-2/

      But sir i am facing issue if i am impinging x-polarized light then how to calculate transmission of 45 degree polarized light using x and y components as suggested in above provided link can u plz help me

    • anna.wirth-singh
      Ansys Employee

      Hi,

      Thanks, I think I understand your question. I agree, it would not be possible to calculate transmission of 45 degree polarized light if strictly x-polarized light is used at the input.

      Would this code snippet accomplish what you would like to achieve?

       

      m="monitor";

       

      Efield=getresult(m,"E"); # returns E vs x,y,z,f

      Hfield=getresult(m,"H");

       

      E=pinch(Efield.E); # returns just E field

      H=pinch(Hfield.H);

       

      x=Efield.x; # monitor x sampling

      y=Efield.y;

      z=Efield.z;

       

      Ex=pinch(E(:,:,1));

      Ey=pinch(E(:,:,2));

      Ez=pinch(E(:,:,3));

      Hx=pinch(H(:,:,1));

      Hy=pinch(H(:,:,2));

      Hz=pinch(H(:,:,3));

       

      poynting=Ex*conj(Hy)-Ey*conj(Hx);

       

      Then you can select the desired components of the Poynting vector and integrate to find the power transmitted through the monitor component. Is this on the right track with what you want to achieve?

       

      Best,

      Anna

       

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