Analysis Group

This section introduces how to create an analysis group.

Creating an Analysis Group

Design Ideas of Analysis Group

The following example elaborates on design idea of analysis group, which converts electric field vector in rectangular coordinate system into electric field vector in spherical coordinate system.

Theoretical Analysis

Convert electric field vector in rectangular coordinate system from 2D monitor into that in spherical coordinate system. Conversion formula for electric field vector in rectangular coordinate system to that in the spherical coordinate system is known as:

$\begin{aligned} \\ &E_r = E_x sin\theta cos\phi+ E_y sin\theta sin\phi + E_z cos\theta\\ &E_\theta = E_x cos\theta cos\phi+ E_y cos\theta sin\phi - E_z sin\theta\\ &E_\phi = - E_x sin\phi + E_y cos\phi \end{aligned}$

Creating an Analysis Group

1.Set coordinate origin of analysis group;

2.Add variables required to create a monitor (or source). Monitor records simulation data that can be input data for post-processing;

3.Create a script that can generate/create a monitor (or source), and edit and run script program;

4.Create names of parameter variables and result variables;

5.Edit corresponding scripts in Script window.

Testing Results

Compare vector diagrams (a) about the electric field and decomposed vector diagrams (b) about the electric field:

Analysis Library

Software has a built-in analysis library to facilitate users to deal with some complex post-processing issues.

Built-in Analysis Group

Electric Displacement Field

Name	Description	Application
D	Used to calculate electric displacement vector.	FDTD, FDFD
D_adv	Used for advanced calculations of electric displacement vector. Note: monitor's spatial interpolation is None.	FDTD, FDFD

Bandstructure

Name	Description	Application
Bandstructure	Calculate the bandstructure of a specified structure.	FDTD
Dipole clouds	Generate a pre-defined number of dipoles, where position, phase, and orientation of each dipole are randomly distributed.	FDTD, FDFD

Data Representation

Name	Description	Application
Curve monitor	An arc-shaped monitor formed by a set of point monitors, where each point monitor is at the same distance from center of the circle.	FDTD, FDFD
E outline	Analysis group uses Index and FDFP monitors to obtain the electric field distribution containing the structure contours.	FDTD, FDFD

Far Field

Name	Description	Application
Far field from a closed box	Calculate far-field data from near-field data according to the equivalence principle.	FDTD, FDFD
Directivity	Calculate directivity from near-field data according to the equivalence principle.	FDTD, FDFD

Optical Force

Name	Description	Application
OF_MST	Calculate optical force by MST method.	FDTD, FDFD
OF_V	Calculate optical force by volume method.	FDTD, FDFD

Other Physical Quantities

Name	Description	Application
Thermal emission	Calculate thermal emission power.	FDTD, FDFD
Current charge density	Calculate charge density and current density.	FDTD, FDFD
Induced current	Calculate induced currents.	FDTD, FDFD
Resistance heat	Calculate the resistance heat distribution.	FDTD, FDFD

Optical Power

Name	Description	Application
Cross section	Calculate scattering cross-section, absorption cross-section, and extinction cross-section.	FDTD, FDFD
Power absorbed	Calculate absorptivity of a certain volume of material.	FDTD, FDFD
Power absorbed advanced	Calculate absorptivity of a certain volume of material. This method is suitable for engineering on metal or other high absorption materials.	FDTD, FDFD
Transmission box	Calculate transmission power of a closed box.	FDTD, FDFD

Photoelectric Effect

Name	Description	Application
Generation rate	Used to calculate photon generation rate.	FDTD, FDFD
Quantum efficiency	Used to calculate quantum efficiency (QE) and radiative decay rate (gamma).	FDTD, FDFD

Resonator

Name	Description	Application
High Q analysis	Calculate high quality factor.	FDTD
Low Q analysis	Calculate low quality factor.	FDTD
Mode area	Calculate modal area of a confined mode.	FDTD, FDFD
Mode volume	Calculate modal volume of a confined mode.	FDTD, FDFD

Using Analysis Group

Add an analysis group, taking directivity analysis group as an example.

Based on simulation requirements, set parameters of analysis group as:

For both full-space/grounded situations, results of far-field directivity are: