expand - Script command – Ansys Optics

FDTD MODE

Returns the expansion coefficients between the fields recorded at two arbitrary DFT monitors, saved in two D-CARDs, or saved in two rectilinear datasets. The coefficients are defined according to:

$$ \begin{array}{l}{a=0.25 *\left(\frac{\int d \mathbf{S} \cdot \mathbf{E}_{1} \times \mathbf{H}_{2}^{*}}{N}+\frac{\int d \mathbf{S} \cdot \mathbf{E}_{2}^{*} \times \mathbf{H}_{1}}{\operatorname{conj}(N)}\right)} \\ {b=0.25 *\left(\frac{\int d \mathbf{S} \cdot \mathbf{E}_{1} \times \mathbf{H}_{2}^{*}}{N}-\frac{\int d \mathbf{S} \cdot \mathbf{E}_{2}^{*} \times \mathbf{H}_{1}}{\operatorname{con} j(N)}\right)} \\ {N=0.5^{*} \int d \mathbf{S}\cdot \mathbf{E}_{2} \times \mathbf{H}_{2}^{*}} \\ {P=0.5 * \int d \mathbf{S} \cdot \mathbf{E}_{1} \times \mathbf{H}_{1}^{*}}\end{array} $$

For more detail on how to use this command, definitions on the parameters and how to interpret the results, please see Using Mode Expansion Monitors . Note that real(N) is the power of the waveguide mode. conj(N) is equal to N if this is a real number. For the unconjugated coefficients, see expand2 .

Syntax

Description

expand(mode1,mode_ref,x,y,z);

Outputs the expansion coefficients between the fields of two modes

mode1, mode_ref: field information, with $\mathbf{E}_{1}$,$\mathbf{H}_{1}$ contained in mode1, and $\mathbf{E}_{2}$,$\mathbf{H}_{2}$ contained in mode_ref. Can be in one of the following formats:
1. 1. Frequency domain monitor names, string input, e.g. “monitor1”
  2. Mode D-CARDs containing field information, string input, e.g. “mode1”
  3. Rectilinear datasets, see below for more information
x,y,z: spatial displacement of the fields from monitor1 with respect to those from monitor_ref

Using Rectilinear Datasets

Starting in 2024R2.3, rectilinear datasets with arbitrary field profiles are supported in addition to monitor names and D-CARDs.

Rectilinear datasets cannot be mixed with other input types, however, data can be extracted from modes using the getresult script command, shown in the examples below.

When using rectilinear datasets, they should contain attribute names ‘E’ and ‘H’, which will be used as the electric and magnetic fields, respectively. If no attribute name ‘E’ is found, the first attribute of the dataset is assumed to be the electric field. If no attribute ‘H’ is found, the first attribute of the dataset after the electric field attribute is assumed to be the magnetic field.

Example

The following script expands the fields from monitor "R" onto the reference monitor "R_ref":

M = expand(“R”,"R_ref”,0,0,0);
f = getdata(“R”,”f”);
a = pinch(M,1,1);
b = pinch(M,1,2);
n = pinch(M,1,3);
p = pinch(M,1,4);
S11 = b;

The following script expands the fields from monitor “R” onto reference monitor “R_ref” by first converting them to rectilinear datasets using getresult. The result is identical to above.

# example using rectilinear datasets
#First, obtain rectilinear dataset from monitors using getresult
#These datasets could have been imported from elsewhere as well
EH1 = getresult("R","E");
H1 = getresult("R","H");
EH1.addattribute("H",H1.H);
EH2 = getresult("R_ref","E");
H2 = getresult("R_ref","H");
EH2.addattribute("R_ref",H2.H);

M = expand(EH1,EH2,0,0,0);
f = EH1.f;
a = pinch(M,1,1);
b = pinch(M,1,2);
n = pinch(M,1,3);
p = pinch(M,1,4);
S11 = b;

expand - Script command

Using Rectilinear Datasets

Associated files

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