Variable Descriptions
Descriptions of all variables available in the simulation file. Some variables have an alias, which is a copy of the data from the primary variable name for enhanced compatability with previous versions of EMode. The * indicates an name that is defined by the user.
- background_refractive_index
(float) Refractive index in the background of simulation window, setting the default refractive index where no shapes are defined.
- bend_radius
(float) [nm] Bend radius of the waveguide; 0 indicates that no bend is applied.
Alias:
radius
- boundary_condition
(str) Boundary condition for the simulation window; 0 indicates a metal boundary and A or S indicate asymmetric or symmetric Ex; the first character indicates x-direction and the second character indicates the y-direction boundary condition.
Alias:
BC
- confinement_window
(list) The confinement factor for each specified mode is saved under this variable only when the confinement region is specified with a list of vertices, instead of a specific shape.
- effective_area
(list) The effective area of each waveguide mode in units of square microns (\(\mu \mathrm{m}^2\)), calculated by the following equation.
\[A_\mathrm{eff} = \frac{\left( \iint \left| \vec E \right|^2 \, \mathrm{d}x \, \mathrm{d}y \right)^2}{\iint \left| \vec E \right|^4 \, \mathrm{d}x \, \mathrm{d}y}\]
- effective_index
(list) The real part of the effective index for each mode.
Alias:
n_eff
- Ex
- Ey
- Ez
- Hx
- Hy
- Hz
(complex arrays) The electric (E [V/nm]) and magnetic (H [A/nm]) fields in the x-, y-, and z-directions. These calculated fields are interpolated to the center point of each mesh grid (defined by
xandy). The fields are normalized to the equation below.\[\frac{1}{2} \mathrm{Re} \iint \left( \vec E \times \vec H^* \right) \! \cdot \! \hat{z} \, \mathrm{d}x \, \mathrm{d}y = 1 \, \mathrm{W}\]
- expansion_resolution
(list) List of the desired mesh step size in the x- and y-directions in the expanded regions around the perimeter of the simulation window.
- expansion_size
(list) List of the size of the expanded regions in the x- and y-directions.
- field_to_solve
(str) Desired transverse field component to solve; either ‘Et’ or ‘Ht’.
- Fx
- Fy
(complex arrays) Raw fields that are solved. They either correspond to the electric or magnetic fields depending on
field_to_solve. However, these raw fields are defined on the Yee mesh grid, not the center points of the mesh grid. An internal function extracts all other field components fromFx,Fy,permittivity, andpermeability.
- group_index
(list) The group refractive index calculated for each mode.
Alias:
n_g
- loss_dB_per_m
(float) [dB/m] The power loss coefficient (\(\alpha\)), which relates to the imaginary part of the effective index (\(\kappa\)) by the following equation with the wavelength (\(\lambda\)).
Alias:
alpha\[\kappa = \frac{\alpha \lambda}{(4 \pi) 10 \, \mathrm{log}_{10}(e)} \approx \frac{\alpha \lambda}{54.575}\]
- mesh_complete_bool
(boolean) Indicates if the mesh grid has been calculated for the current definition of shapes and settings.
- num_modes
(int) Total number of modes to solve.
- num_pml_layers
(int or list) Either an integer or a list of integers indicating the number of perfectly matched layers for all or each boundary: [North, South, East, West].
- max_effective_index
(float) Upper limit for the effective index.
- overlap
(list) The overlap integral in
overlapuses the following formula to calculate the modal excitation of \(\vec E_2\) by \(\vec E_1\).Coldren, Larry A., Scott W. Corzine, and Milan L. Mashanovitch, ‘’Diode lasers and photonic integrated circuits,’’ John Wiley & Sons, 2012.
\[\mathrm{overlap} = \frac{4 n_\mathrm{eff,1} n_\mathrm{eff,2}}{(n_\mathrm{eff,1} + n_\mathrm{eff,2})^2} \frac{\left| \iint \vec E_2^* \cdot \vec E_1 \, \mathrm{d}x \, \mathrm{d}y \right|^2}{\iint \left| \vec E_1 \right|^2 \, \mathrm{d}x \, \mathrm{d}y \, \iint \left| \vec E_2 \right|^2 \, \mathrm{d}x \, \mathrm{d}y}\]
- permittivity
- permeability
(list) The permittivity and permeability arrays are defined by
meshfrom the current shapes and settings. Each is a list of arrays defining the corresponding parameters in the x-, y-, and z-directions.
- pml_modes_removed
(list) Mode indices that were removed during the automatic process to determine artificial modes introduced from the pml layers.
- pml_NSEW_bool
(list) List of booleans indicating if a perfectly matched layer (pml) boundary condition is applied to the each boundary: [North, South, East, West].
- remove_pml_modes_bool
(bool) Indicates whether or not to automatically remove artificial modes found in the pml layers.
- shape_list
(list) Complete list of defined shapes.
- shape_NAME_confinement
(list) Confinement factor for each mode in the corresponding shape.
- shape_NAME_edges
(list) Definitions of edges for the corresponding shape where the scattering loss is calculated. These edges can be correlate to the loss values from
shape_NAME_scattering_all_edges.
- shape_NAME_etch_depth
(float) The etch depth associated with a ‘planar’ shape that also has a defined
shape_NAME_mask. The shape will have a thickness outside the mask definition equal to the difference between theshape_NAME_heightandshape_NAME_etch_depth(or zero if this is negative).
- shape_NAME_fill_permeability
(float or str) Either a value or a material name to define the permeability in the etched region of a ‘planar’ shape.
- shape_NAME_fill_refractive_index
(float or str) Either a value or a material name to define the refractive index in the etched region of a ‘planar’ shape.
- shape_NAME_height
(float) Maximum size of the shape in the y-direction.
- shape_NAME_loss_dB_per_m
(float) [dB/m] Absorption coefficient for power loss in the region defined by the shape.
- shape_NAME_mask
(float or list) Width of the a mask for etching a ‘planar’ shape. Also accepts a list to define both the width and the x-offset of the mask.
- shape_NAME_name
(str) User-defined name of the shape. This name will be used to reference this shape in subsequent functions.
- shape_NAME_permeability
(float or str) Either a value or a material name to define the permeability of the shape.
- shape_NAME_position
(list) The x- and y-positions of the center point of the shape, constrained by the
shape_NAME_widthandshape_NAME_width.
- shape_NAME_priority
(float) A value that defines the order in which the shape is drawn relative to other shapes. A higher value give a higher priority, putting the shape in front of other shapes with lower priority.
- shape_NAME_refractive_index
(float or str) Either a value or a material name to define the refractive index of the shape.
- shape_NAME_refractive_index_value
(float) The value of the refractive index for the shape. This is useful as a reference when a material name is passed for
shape_NAME_refractive_index.
- shape_NAME_scattering_all_edges
(list) Calculated scattering loss for each edge of the shape, defined by
shape_NAME_edges.
- shape_NAME_scattering_horizontal_edges
(list) Calculated scattering loss for each horizontal edge of the shape.
- shape_NAME_scattering_sum
(list) Total calculated scattering loss for all edges of the shape.
- shape_NAME_scattering_vertical_edges
(list) Calculated scattering loss for each vertical edge of the shape.
- shape_NAME_shape_type
(str) The shape type is either ‘planar’, ‘conformal’, ‘polygon’, or ‘ellipse’.
- shape_NAME_sidewall_angle
(float) [degrees] Angle of the side wall for a ‘planar’ shape relative to a vertical at 0 degrees.
- shape_NAME_vertices
(list) Pairs of [x,y] vertices that define the perimeter of a shape.
- shape_NAME_width
(float) Maximum size of the shape in the x-direction.
- Sx
- Sy
- Sz
(arrays) [W/nm] The Poynting vector in the x-, y-, and z-directions.
- TE_fraction
(list) Fractions representing how much the mode is like a TE mode, calculated with the following equation.
\[\mathrm{{TE_fraction}} = \frac{\iint \left| \vec E_\mathrm{x} \right|^2 \, \mathrm{d}x \, \mathrm{d}y}{\iint \left| \vec E_\mathrm{x} \right|^2 + \left| \vec E_\mathrm{y} \right|^2 \, \mathrm{d}x \, \mathrm{d}y}\]
- TE_indices
- TM_indices
(list) Indices for the corresponding TE or TM modes in the modes list.
- tolerance
(float) Numerical tolerance for convergence of the effective indices.
- user_material_*
(str) The name of a user defined material.
- wavelength
(float) [nm] Free-space wavelength.
- window_height
(float) [nm] Total height (y-direction) of the simulation window.
- window_width
(float) [nm] Total width (x-direction) of the simulation window.
- x
- y
(complex arrays) Arrays that define the x and y grid center points of the mesh. These can be complex when pml layers are introduced.
- x_edge
- y_edge
(complex arrays) Arrays that define the x and y grid edge points of the mesh. These can be complex when pml layers are introduced.
- x_resolution
- y_resolution
(float) [nm] Mesh grid step in the x- and y-directions.