Learning Forum

[Kawshik Nath]

How can i draw this type of inverted pyramid structure in Lumerical fdtd. The structure is given below.

[Afroditi Petropoulou]

Dear Kawshik,

Thank you for contacting us!

If I understand correctly, this is a substrate with etched material in pyramid shape. This means that the material of the pyramids is air. If this is the case then you can create a new structure group where you will define the substrate by inserting a rectangle and an array of pyramids. The material of the pyramids should be set to etch.

An example of such a structure group is the following:

The x_span and y_span parameters are the x and y length of the base of each pyramid. The z_span is the pyramid height. The x_period and y_period is the number of pyramids in the x and y direction.

The x_span_rect, y_span_rect and z_span_rect are the dimensions of the substrate.

After inserting these parameters in the "Properties" tab, you can add the following script in the "Script" tab:

 

deleteall;

for (i=1:y_period) {

  for (j=1:x_period) {

    addpyramid;

    set("x",(x_span/2)+(j-1)*x_span-x_period*x_span/2);

   set("y",(y_span/2)+(i-1)*y_span-y_period*y_span/2);

   set("x span bottom",x_span);

   set("x span top",0);

   set("y span bottom",y_span);

   set("y span top",0);

   set("z span",z_span);

   set("material","etch");

  }

}

addrect;

set("x span",x_span_rect);

set("y span",y_span_rect);

set("z min",-z_span/2);

set("z max",-z_span/2+z_span_rect);

 

You can also add an index monitor to check the results.

 

Best Regards,

Afroditi