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Application Gallery

This page contains detailed instructions on how to create the project file in the FEEM.  Alternatively the project file provided in the top-level page can be used to go through the steps in the Results and Discussion page.

Material Database

Open a blank simulation file in the FEEM.  Under the Material section of the Design tab of the tabbed toolbar, click on the Optical button icon_device_optical_material_zoom94 to open the optical material database.  The material database contains more than 40 different optical models for common materials. The user can also add new material models to the database using the "New Material" button.  Additionally, material models can be imported from other FEEM, FDTD, or MODE project files using the "Import material" button.

 

Materials

 

For this simulation we will use two simple dielectric materials, "core_material" and "cladding_material", created from the Dielectric material in the Optical Material Database and added to materials in the Objects Tree. To do this you have two options:

 

1. Under the Materials section of the Design tab, click on New Material button icon_design_newmaterial_zoom94. Then right click on recently added New Material under the Material Group in Objects Tree and click on Add optical properties. This will automatically open Optical Material Database. Scroll down to find Dielectric from Material List, modify the Refractive index value to 1.44 and then click on the Select button. This will add the material along with its optical properties to the objects tree.

 

2. Click on the Optical button icon_device_optical_material_zoom94 to open the optical material database. Select Dielectric, modify the Refractive index value to 1.44 and then click on Create button as is shown below:

 

step_index_fiber_material_add_zoom60

 

This will add the optical properties of the core material into the Objects Tree. After adding the properties, you can rename the new material by double clicking on its name or right click and then select rename. For convenience, rename the material object to "core_material". The same procedure can be followed to create "cladding_material", which will be a simple dielectric with refractive index 1.4. For visualization purposes, pick a different color for the cladding material so that the two different materials can be easily recognized.

 

Geometry

The Structures section of the Design tab icon_structures_tab_zoom64  can be used to introduce various types of structures into the simulation space.  The available options vary from simple rectangles and spheres to complex waveguides and planar solids. In this example, we will use two overlapping cylinders to define the fiber core and the surrounding fiber cladding.

 

core

From the Structures section of the Design tab, select a CIRCLE to be added to the Objects Tree. Select the circle in the Objects Tree and click on the "Edit Properties" button icon_edit to edit the properties of the circle according to the following table.

 

tab

property

value


name

core

Geometry

x (um)

0


y (um)

0


z (um) / z span (um)

0 / 1.1


radius (um)

10

Material

material

core_material

 

cladding

From the Structures section of the Design tab, select another CIRCLE to be added to the Objects Tree. Select the circle in the Objects Tree and click on the "Edit Properties" button icon_edit to edit the properties of the circle according to the following table. Note the mesh order is set to 5 (a higher number than the default 2) so that the "cladding" structure will not fill the volume where it overlaps with the "core" structure. The z span of the "cladding" is set to be slightly smaller than that of the "core" so that the latter is not hidden by the former in the viewport; alternatively, you can use an alpha value less than 1 in the Graphical rendering tab of the "cladding" properties to make the object semi-transparent.

 

tab

property

value


name

cladding

Geometry

x (um)

0


y (um)

0


z (um) / z span (um)

0 / 1


radius (um)

17.5

Material

material

cladding_material


mesh order

5

Graphical rendering

alpha

0.5

 

 

Simulation Region

Click on icon_simulation_region in the Objects Tree and click on the icon_edit button (on the left of the Objects Tree) to edit its properties according to the following table. Note that the simulation region size is such that the cladding cylinder is completely inside and the simulation region boundaries are all set to open. The purpose is to assign the simulation boundary conditions to the outer surface of the cladding circle (see Boundary Conditions).

 

tab

property

value

General

dimension

2D Z-Normal


x min boundary

open


x max boundary

open


y min boundary

open


y max boundary

open

Material

background material

None

Geometry

x (um) / x span (um)

0 / 35


y (um) / y span (um)

0 /35


z (um)

0

 

 

FEEM Solver Region

In the Solvers section of the Design tab select the "FEEM" button to place an FEEM solver in the simulation environment.  Note that once the solver is selected, all the simulation objects (i.e. constraints, boundary conditions, etc.) belonging to the solver become available under a new tab named FEEM.  Select the FEEM object from the Objects Tree and click on the "Edit Properties" button icon_edit to edit the properties according to the following table.

 

tab

property

value

General

simulation region

simulation region

Mesh

edges per wavelength

0.4


refine based on material properties

disabled


polynomial order

3

Modal Analysis

sweep type

single > wavelength


wavelength (um)

1.55


number of trial modes

20


use max index

enabled

 

 

Check Partitioned Volume

The basic simulation setup is ready. Next, click on the "Partition simulation region" button icon_partition to view the partitioned volume (see figure below).  The partitioned volume mode shows the entire simulation volume and identifies the different domains and surfaces.  Each domain and surface has a unique identifier and they are listed under the "simulation region" in the Objects Tree.  As you select different domains and surfaces in the Objects Tree the corresponding volume or surface gets highlighted in the partitioned volume.  In the figure below "domain 2" is highlighted in the partitioned volume.

 

step_index_fiber_partition_zoom60

 

Mesh Constraint

In Solver section under the FEEM tab, press on the CONSTRAINT button icon_CHARGE_constraint to add a Mesh Constraint to the objects tree.  Select it from the Objects Tree (under FEEM) and click on the "Edit Properties" button icon_edit to edit the properties according to the following table.

section

property

value


name

fiber_mesh

General

Maximum edge length (um)

0.8

Geometry

geometry type

surface


surface type

solid


solid

core


outer surface only

enabled

 

Boundary Conditions

The last step in setting up the simulation is to add the boundary conditions at the simulation boundaries. In most FEEM simulations, the boundaries are defined as perfect electrical conductors using the PEC boundary condition (which is also the default option).

 

Click on the PEC button in the Boundary Conditions section under the FEEM tab in the tabbed toolstrip and add a PEC object in the objects tree.  Click on the "Edit Properties" button icon_edit to edit the properties according to the following table.

 

tab

property

value


name

PEC

Geometry

surface type

solid


solid

cladding


outer surface only

enabled

 

 

Error Check

The project file is now set up. As a final step, you can use the "Check" icon_DEVICE_check button to identify potential issues in your simulation. This will open up the "Error Checking and Diagnostics" window that shows any error in the simulation setup as well information about the different simulation objects. There should be no warnings. Finally, save the file using the "File" menu and run it by following the instructions provided in Results and Discussion.

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