Returns the overlap and power coupling between two modes calculated by the FDE solver or recorded by frequency monitors from an FDTD or varFDTD simulation, or field profiles recorded in rectilinear datasets.
Overlap measures the fraction of electromagnetic fields that overlap between the two field profiles (modes). This is also the fraction of power from mode2 that can propagate in mode1 (for both forward and backward propagating fields). The absolute value of the entire formula is to ensure it is positive.
$$ {\text { overlap }=\left| \operatorname{Re} \left[\frac{(\int \mathbf{E}_{1} \times \mathbf{H}_{2}^{*} \cdot d \mathbf{S}) (\int \mathbf{E}_{2} \times \mathbf{H}_{1}^{*} \cdot d \mathbf{S} ) }{\int \mathbf{E}_{1} \times \mathbf{H}_{1}^{*} \cdot d \mathbf{S} }\right] \frac{1}{ \operatorname{Re} ( \int \mathbf{E}_{2} \times \mathbf{H}_{2}^{*} \cdot d \mathbf{S} )} \right| } $$
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Syntax |
Description |
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out = overlap(mode2, mode1); |
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out = overlap(mode2, mode1, x, y,z); |
Mode alignment can be adjusted before overlap is calculated.
The offset is applied to the second mode listed, i.e. ‘mode1’ in this case. All inputs (FDE mode names, frequency monitors, rectilinear datasets) are valid also for the syntax with alignment adjustment. |
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.
Examples
This example shows how to use the overlap command to calculate the overlap and power coupling between two modes.
copydcard("mode1","test_mode1");copydcard("mode2","test_mode2");
out = overlap("test_mode1","test_mode2");
?out(1); # overlap
?out(2); # power coupling
#The same result as above, but using rectilinear datasets
EH1 = getresult("mode1","E"); #getresult used to extract E and H data
H1 = getresult("mode1","H");
EH1.addattribute("H",H1.H);
EH2 = getresult("mode2","E");
H2 = getresult("mode2","H");
EH2.addattribute("H",H2.H);
out2 = overlap(EH1,EH2);
?out2(1); # overlap
?out2(2); # power coupling
See Also
List of commands , copydcard , findmodes , coupling , bestoverlap , propagate , expand , expand2 , optimizeposition