Learning Forum

[Jeb song]

I wanted to ask about the expand function: https://optics.ansys.com/hc/en-us/articles/360034926653-expand-Script-command

Suppose we compose the total electric field in two modes, so E_out = cE_1 + dE_2.

As described in the expand function example, after setting M=expand(E_out, E_1, 0, 0, 0), is it the case that pinch(M,1,1) = c?

Likewise for M=expand(E_out, E_2, 0, 0, 0), so that pinch(M,1,1) = d?

[Guilin Sun]

expand('monitor1','monitor_ref',x,y,z); 

It decomposes the monitor_1 data into the base mode from monitor_ref. You may need to refer to this  Using Mode Expansion Monitors

to get inofrmaiton for the result of a,b,n,p.

So it is not the simple coefficients c and d as you expected.

 

 

 

[Jeb song]

How would I be able to obtain c, d instead? The overlap function doesn't work since it doesn't give the complex coefficients.

[Guilin Sun]

It is a little different:

for you,  E_out = cE_1 + dE_2. you mean the total field is composed of E_1 and E_2, and theie amplitude weight is c and d.

However, the "expand" uses a reference mode as the decompose base, say Eref. "Expand" will tell you how much of E_out is matched with E_Eref.

In order to get c and d, you will need to E_ref. one is E_1, and the second one if E_2.

Thus, c,d should be one of the two: a or b. 

Their definition is here  https://optics.ansys.com/hc/en-us/articles/360034902433-Using-and-understanding-Mode-Expansion-Monitors

I hope this clarifies the concept.

 

[Jeb song]

Thanks for the clarification. Does this mean that for M=expand(E_out, E_1, 0, 0, 0), the output for the a should match the amplitude weight c (and vice versa for E_2)?

[Guilin Sun]

not necessarily , because "a" is the coeffect along positive axis and "b" is for negative axis. details can be found in the above link.