## Photonics

Topics related to Lumerical and more

#### Calculate far-field from electric field?

• Albi.Pani
Subscriber

Hi, for a particular type of problem I need to combine electrical field from different wavelengths in this way:

switchtolayout;

setnamed("source","frequency",w);

setnamed("source_1","frequency",w);

run;

E1z = getdata("tras", "Ez");

E1y = getdata("tras", "Ey");

switchtolayout;

setnamed("source","frequency",2*w);

setnamed("source_1","frequency",2*w);

run;

E2z = getdata("tras", "Ez");

E2y = getdata("tras", "Ey");

EtotZ = (((E1z)^2)*(E2z))^1; EtotY=(((E1y)^2)*(E2y))^1;

The EtotX component is zero. "tras" is the name of a frequency-domain field and power monitor. Can I calculate the far-field of the field Etot=(EtotX, EtotY, EtotZ) ? How can I do? I have seen only examples starting from the monitor information

• Guilin Sun
Ansys Employee

Unfortunately the far field cannot be obtained from the E-field only, as the theory requires H-field at the same time.

You can

1: project to the farfield after each simulation, then add them with the intensity quantities. But it seems you have specail manipulation of the fields, not directly sum them. I am not sure what is the physics to manipulate the farfields that way.

2:  use the total fields of Ex,Ey and Ez to calculate H fields through the discrete Maxwell Equations. However it needs more monitors to get the difference out of the moitor plane. This method is not that easy and the result may depend on the mesh accuracy and monitor distance. The distance of the two monitors should be in one mesh, exactly.

This is not something people do commonly.

However

• Albi.Pani
Subscriber

Ok, thank you