There are several types of simulation objects in FDTD Solutions, MODE Solutions' propagator, MODE Solutions' Eigenmode Solver and DEVICE. These objects are used to model the physical structure, define the solver region, any sources of light or doping/generation regions as well as monitors to collect data.
The following sections provide detailed descriptions of each simulation object. Each simulation object can be added by clicking on the corresponding icon in the GUI.
For example, in the screen shot on the right, clicking on the button would add a circle physical structure object.
Once the object is selected, pressing the EDIT button will bring up a window where it is possible to modify the properties of the simulation object. The corresponding window for the circle object is shown below.
TIP: In-field equation interpreter
wish to set a value to the square root of 3 divided by e, just enter sqrt(3)/exp(1) into the field. For more information, see the Equation interpreter section.
Notes:
Structure objects support Multi-object editing. If you select multiple objects then click EDIT, you can edit properties that are common to all of the selected objects.
Monitors and sources have some global properties that apply to many objects. For example, the global source frequency range can be applied to all sources. The global properties can be edited with the GLOBAL PROPERTIES button.
Groups
Simulation objects can be organized into various types of groupings.
Container Group
A container group is the simplest type and can contain all object types as well as other groups. This object acts like a simple folder allowing the user to collapse and expand its contents in the object tree. Its only user setting is a position offset in x,y,z for all contained objects.
Structure Group
Structure groups are one step above container groups in that they allow scripting commands of structures properties. This group contains user-generated variables and scripts that can be utilized to edit and set up parts of the structure. For example, a script can be set up to insert many circles to create a photonic crystal cavity of a certain shape and size. See the Properties tab and Script tab sections for more information. Structure groups can contain other structure groups.
The purpose of this section of the Reference Guide is to describe all of the available simulation objects and their properties. This section is organized as follows. There are five subsections. The first four subsections correspond to the four types of object categories. Each of these sections begins with a brief overview of the simulation objects followed by a description of their property settings. The properties are organized according to the tab that they are located in when the EDIT button is pressed. The last of the five subsections describes the syntax for the equation interpreter.
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5.1
Structures
Structures in a simulation interact with light/electrical sources to produce interesting effects. They are split into 3 groups:
Structures (Primitives)
These are the primitive shapes that make up all structure setups.
Imports
These options open windows that can be used to import structure data from other sources such as pictures or text files.
5.1.1 Primitives
The button includes options to to add the following primitive structures:
Triangle
Triangular objects denote physical objects that appear triangular from above. For 2D simulations, these objects represent triangles while in 3D these objects are extruded in the z direction to a specific height. They are actually polygon objects, with the number of vertices set to 3.
Rectangle
Rectangular regions denote physical objects that appear rectangular from above. For 2D simulations, these objects represent rectangles while in 3D these objects are extruded to a specific height.
Polygon
Polygons allow the user to define a custom object with a variable number of vertices. The location of each vertex can be independently positioned within a plane, and the vertices are connected with straight lines. For 3D simulations, the object is extruded in the z
dimension. In DEVICE, the vertices have to be entered in a counter clock wise manner for the structure to be defined and meshed properly.
Circle
Circles denote physical objects which appear circular or ellipsoid from above. They are either circles/ellipses in 2D, or circular/ellipsoid cylinders in 3D.
Ring
Ring regions represent physical objects that consist of full or partial rings when viewed from above. Rings in 3D simulations are extruded in the z direction to a specific height.
Sphere
In 3D simulations, users can define spherical regions of constant refractive index through the spherical physical object. Spherical objects only exist in 3D simulations.
Pyramid
Pyramids can be configured to half flat tops and/or flat bottoms, and either narrow or expand in the vertical z direction. Pyramids are only available for 3D simulations.
5.1.2 Geometry tab
The geometry tab contains options to change the size and location of the structure.
5.1.3 Material tab
The material options are as follows:
MATERIAL: This field can be set to any material included in the material database. It is possible to include new materials in the database, or edit the materials already included. See the material database section for more information.
OVERRIDE MESH ORDER FROM MATERIAL DATABASE: Select to override the mesh order from the material database and manually set a mesh order. The mesh order is used by the simulation engine to select which material to use when two materials overlap. See the mesh order section for more details.
MESH ORDER: Set the mesh order in this field if the OVERRIDE MESH ORDER FROM MATERIAL DATABASE option is selected. If the option is not selected, the field displays the material's default mesh order from the database. For example, a material of mesh order 1 will take precedence over a material of mesh order 2.
5.1.4 Rotations tab
Rotate objects by setting the following variables:
FIRST, SECOND, THIRD AXES: Select rotation axis. Up to three different rotations can be applied.
ROTATION 1,2,3: The rotation of the object in a clockwise direction about each axis, measured in degrees.
5.1.5 Graphical Rendering tab
The graphical rendering tab is used to change how objects are drawn in the layout editor. The options are:
RENDER TYPE: The options for drawing the objects are detailed or wireframe. Detailed objects are shaded and their transparency can be set using OVERRIDE COLOR OPACITY FROM MATERIAL DATABASE.
DETAIL: This is a slider which takes values between 0 and 1. By default it is set to 0.5. Higher detail shows more detail, but increases the time required to draw objects. This setting has no effect on the simulation.
OVERRIDE COLOR OPACITY FROM MATERIAL DATABASE: When unselected the opacity is determined from the material database. When selected, you can specify a value for ALPHA between 0 (transparent) and 1 (opaque) for the object, depending on how transparent you want the object to be.
5.1.6 Import Data tab
The button includes options to import from a variety of formats:
GDSII
This file format is commonly used to store 2-dimensional geometric data. For details, see
GDSII Import .
5.1.6.1 GDSII Import
The GDSII import function allows you to import structures from a GDSII file into the layout editor. The GDSII file format is commonly used to store 2-dimensional geometric data. This data can be directly imported into a 2D layout environment, or it can be used to import 3D objects into a 3D layout environment by extruding the 2D data in the Z dimension.