Simulation

Our platform offer support for a variety of simulation modules, encompassing both optical and electrical simulation. These may include FDE, EME, FDTD, OEDevice modules, ensuring an expansive electro-optical simulation capabilities.

Use Simulation() to instance a simulation into the project, and then use add function to add simulation solver. The types of solvers available include 'FDE', 'EME', 'FDTD', 'FDTDSmatrix', 'FDTDSweep', 'EMESweep', and 'FDESweep'.

6.1 FDE

The syntax for adding a finite difference eigenmode (FDE) solver to the project and its properties settings are as follows. When adding a FDE solver, it is assumed that the project has already been added, and the pj is an instance of the project. The add function does not return any data.

simu = pj.Simulation()
simu.add(        
        name: str,
        type: Literal["FDE"],
        property: dict
    )

General

Choose the 1D or 2D eigenmode solver, with available types including '2d_x_normal','2d_y_normal','2d_z_normal', 'x_y_prop', 'x_z_prop', 'y_x_prop', 'y_z_prop', 'z_x_prop' and 'z_y_prop'.

Background material

Selects a material object from the material database as the background medium for the simulation region.
refractive_index: If not selecting a material, this field can directly set the refractive index of the background medium. The default value is 1.

Geometry

Parameter	Type	Default	Description
x, y, z	number	-	The center position of the simulation region.
x_span, y_span, z_span	number	-	X span, Y span and Z span of the simulation region.
x_min, x_max	number	-	X min, X max position of the simulation region.
y_min, y_max	number	-	Y min, Y max position of the simulation region.
z_min, z_max	number	-	Z min, Z max position of the simulation region.

Mesh settings

mesh_refinement:
mesh_refinement: Selects 'curve_mesh' or 'staircase' to refine the mesh.

mesh_grading:
grading_factor: The maximum rate at which the mesh size can be changed.

minimum_mesh_step_settings:
min_mesh_step: Specify the minimum mesh size for the entire simulation region, including localmesh region.

global_mesh_uniform_grid:
dx/dy/dz: Specify the maximum grid size along the x, y or z directions throughout the entire simulation region.

Boundary conditions

Select the override default boundary conditions to True, and each boundary condition can be set separately. The optional boundary conditions include "PEC", "PMC", "PML", "symmetric" or "anti symmetric".

Advanced

Dispersion settings: Fractional offset for group delay Remove PML mode settings: Automatically Remove PML Modes Threshold for PML Mode Removal

Example:

The following script adds a FDE solver for the xy plane, sets its dimension and mesh of the simulation area, and run the solver.

simu_name = "FDE_solver"
simu = Project.Simulation() 
simu.add(name=simu_name, type="FDE",
             property={"general": {"solver_type": "2d_z_normal"},
                       "geometry": {"x": 0, "x_span": 3, "y": 0, "y_span": 3, "z": 0, "z_span": 0},
                       "mesh_settings": {"global_mesh_uniform_grid": {"dx": 0.02, "dy": 0.02}}})
simu_res = simu[simu_name].run()

6.2 EME

The syntax for adding an eigenmode expansion (EME) solver to the project and its properties settings are as follows. When adding an EME solver, it is assumed that the project has already been added, and the pj is an instance of the project. The add function does not return any data.

add(        
        name: str,
        type: Literal["EME"],
        property: dict
    )

General

wavelength: The wavelength in the simulation calculation.
use wavelength sweep: Enabling wavelength sweep will automatically calculate the group refractive index of modes in the simulation and allow setting wavelength sweep parameters.

Background material

background_material: Selects a material object from the material database as the background medium for the simulation region. refractive_index: If not selecting a material, this field can directly set the refractive index of the background medium. The default value is 1.

Geometry

Parameter	Type	Default	Description
x_min	number	-	The minimum x position of the EME simulation region.
y, z	number	-	The y and z center position of the EME simulation region.
y_span, z_span	number	-	The y and z span of the EME simulation region.
y min, y max	number	-	The maximum and minimum y position of the EME simulation region.
z min, z max	number	-	The maximum and minimum z position of the EME simulation region.

EME setup

cell_geometry:
energy conservation: Choose the type of energy conservation for the interface S matrix, which is calculated by the modes on both sides of each adjacent cells interface. The options are 'none', 'passive', or 'conserve energy'.

None: Not using energy conservation.
Make passive: If the norm of the interface S matrix is less than or equal to 1, do not perform the operation; otherwise, force norm to be equal to 1.
conserve energy: force the norm of the interface S-matrix to be 1.It is usually used with periodic devices.

allow_custom_eigensolver_settings: Allow you to set different number of modes to be solved for all cell groups, as well as the properties settings for mode analysis.
number_of_modes_for_all_cell_group: Sets the number of modes to be solved for all cells.
cell_group_definition:

Parameter	Type	Default	Description
span	number	-	Sets the span for each cell group.
cell_number	integer	10	Sets number of cells for the cell group.
number_of_modes	integer	10	In the cell group, sets the required number of modes to be solved for all cells.
sc	string	none	Selections are ['none', 'sub_cell']
search	string	max_index	Select 'max_index' or 'near_n' to specify the effective refractive index for mode calculation.

display_groups: Enable displaying the span of each cell group using wireframes to separate them.
display_cells: Enable displaying the boundaries of each cell and use wireframes to separate them.

Mesh settings

Transverse mesh settings

global_mesh_uniform_grid:
dy/dz: The EME solver propagates along the x-axis, so only the mesh step size of the yz plane needs to be set.

Boundary conditions

Advanced

Example:

The following script adds an EME solver, sets its geometry, mesh, background material, and cell geometry settings, and run solver. This script assumes that the structure and EME ports have been added to the project environment.

simu_name = "EME_solver"
simu = Project.Simulation()
simu.add(name=simu_name, type="EME",
        property={"background_material": "object_defined_dielectric", "refractive_index": 1,
                "mesh_settings": {"mesh_factor": 1.2, "mesh_refinement": {"mesh_refinement": "curve_mesh"}},
                "transverse_mesh_setting": {"global_mesh_uniform_grid": {"dy": 0.02, "dz": 0.02}}})
                "geometry": {"x_min": 0, "y": 0, "y_span": 4, "z": 0, "z_span": 3},
                "general": {"wavelength": 1.5, "use_wavelength_sweep": True},
                "eme_setup": {"cell_geometry": {"energy_conservation": "make_passive", "allow_custom_eigensolver_settings": True,
                                                "cell_group_definition": [{"span": 2.5, "cell_number": 1, "number_of_modes": 10, "sc": "none"}]}},
                
simu_res = simu[simu_name].run()

6.3 FDTD

The syntax for adding a finite difference time domain (FDTD) solver to the project and its properties settings are as follows. When adding a FDTD solver, it is assumed that the project has already been added, and the pj is an instance of the project. The add function does not return any data.

add(        
        name: str,
        type: Literal["FDTD"],
        property: dict
    )

General

Dimension: Select the dimension of the simulation region, with options of "2d" and "3d".
Using_optical_path_estimate_time: Use optical path length to estimate simulation duration.
Simulation_time: Set the maximum running time of FDTD solver, in fs units.

Background material

background_material: Selects a material object from the material database as the background medium for the simulation region.
refractive_index: If not selecting a material, this field can directly set the refractive index of the background medium. The default value is 1.

Geometry

Parameter	Type	Default	Description
x, y, z	number	-	The center position of the simulation region.
x_span, y_span, z_span	number	-	X span, Y span and Z span of the simulation region.
x_min, x_max	number	-	X min, X max position of the simulation region.
y_min, y_max	number	-	Y min, Y max position of the simulation region.
z_min, z_max	number	-	Z min, Z max position of the simulation region.

Mesh settings

mesh_type: The types of mesh generation algorithms available for FDTD solver are "auto_non_uniform' and 'uniform'.

mesh_accuracy：
cells_per_wavelength: Using the wavelength in the material to set the mesh size, with cells per wavelength limited to integer >=6.

mesh_step_settings:
dx/dy/dz: Allow setting the grid step size in the x/y/z direction when selecting uniform type mesh.

mesh_refinement:
mesh_refinement: Selects 'curve_mesh' or 'staircase' to refine the mesh.

mesh_grading:
grading: After activation, the growth rate of mesh size can be customized.
grading_factor: The maximum rate at which the mesh size can be changed.

minimum_mesh_step_settings:
min_mesh_step: Specify the minimum mesh size for the entire simulation region, including localmesh region.

Boundary conditions

advanced_options.

auto_shutoff:
use_early_shutoff: Use the conditions of shutoff to terminate the simulation in advance.
auto_shutoff_min: When the total energy in the simulation region drops to this fraction, the simulation will end.
down_sample_time: Check the early shutoff conditions for each down sample time step.

Example:

The following script adds a FDTD solver, sets its simulation time, background material, geometry, and mesh settings, and run solver. This script assumes the structure, source and monitor have been added to the project environment.

simu_name = "FDTD_solver"
simu = Project.Simulation()
simu.add(name=simu_name, type="FDTD",
            property={"general": {"simulation_time": 1000},
                      "background_material": 'object_defined_dielectric', "refractive_index": 1,
                      "geometry": {"x": 0, "x_span": 6, "y": 0, "y_span": 3, "z": 0, "z_span": 3 },
                      "boundary_conditions": {"x_min_bc": "PML", "x_max_bc": "PML", "y_min_bc": "PML", "y_max_bc": "PML", "z_min_bc": "PML", "z_max_bc": "PML",
                                            "pml_settings": {"all_pml": {"layers": 8, "kappa": 2, "sigma": 0.8, "polynomial": 3, "alpha": 0, "alpha_polynomial": 1}}},
                      "mesh_settings": {"mesh_factor": 1.2, "mesh_type": "auto_non_uniform",
                                        "mesh_accuracy": {"cells_per_wavelength": 10},
                                        "minimum_mesh_step_settings": {"min_mesh_step": 1e-4},
                                        "mesh_refinement": {"mesh_refinement": "curve_mesh"}}})
simu_res = simu[simu_name].run()

6.4 FDESweep

The syntax for adding FDESweep solver to the project and its properties settings are as follows. When adding a FDESweep solver, it is assumed that the FDE solver and FDE analysis have already been added, and the pj is an instance of the project. The add function does not return any data.

add(        
        name: str,
        type: Literal["FDESweep"],
        property: dict
    )

Simulation name

Specifies the name of the simulation solver used for parameter sweep.

sweep type

Selects the type of parameter sweep settings, with options of "ranges" and "values".

Parameters

Variable: Specifies the global parameter names used in the simulation.
Number_of_points: When using the sweep type of ranges, the number of variable changes in parameter sweep.
Start/Stop: When using the sweep type of ranges, sets the start and stop value of the variable.
Values: When using the sweep type of values, specifies the sweep values by a list.

Result

name: Specifies the name of the parameter sweep result.
result: Specifies the name of the analysis that has been added.
component: Specifies the result component to be extracted.

Example: The following script adds a FDESweep solver to obtain the effective refractive index of FDE analysis results, where the sweep range must be set through global parameters. This script assumes that the FDE solver and FDE analysis have been set up.

simu_name = "FDE_Solver"         # The name of FDE solver
analysis_name = "FDE_Analysis"   # The name of FDE analysis
sweep_name = "FDE_Sweep"         # The name of FDE sweep
para = pj.GlobalParameter()
width = para.add(name="width", expression=0.5, description='')  # The setting of parameter sweep must use global parameters.
simu = pj.Simulation()
simu.add(name=sweep_name, type="FDESweep",
             property={"simulation_name": simu_name,
                       "sweep_type": "ranges", 
                       'parameters': [ {'variable': width, 'number_of_points': 3, 'start': 0.5, 'stop': 0.6} ],
                        "result": [{"name": "Neff", "result": analysis_name, "component": "mode0/neff"}]})
swp_res = simu["FDESweep"].run()

6.5 EMESweep

The syntax for adding EMESweep solver to the project and its properties settings are as follows. When adding an EMESweep solver, it is assumed that the EME solver and EME analysis have already been added, and the pj is an instance of the project. The add function does not return any data.

add(        
        name: str,
        type: Literal["EMESweep"],
        property: dict
    )

Simulation name

Specifies the name of the simulation solver used for parameter sweep.

Sweep type

Selects the type of parameter sweep settings, with options of "ranges" and "values".

Parameters

Result

name: Specifies the name of the parameter sweep result.
result: Specifies the name of the analysis that has been added.
component: Specifies the result component to be extracted.

Example:

The following script adds an EMESweep solver to obtain the S-Matrix of EME analysis results, where the sweep range must be set through global parameters. This script assumes that the EME solver and EME analysis have been set up.

simu_name = "EME_Solver"         # The name of EME solver
analysis_name = "EME_Analysis"   # The name of EME analysis
sweep_name = "EME_Sweep"         # The name of EME sweep
para = pj.GlobalParameter()
gap = para.add(name="gap", expression=0.45, description='')  # The setting of parameter sweep must use global parameters.
simu = pj.Simulation()
simu.add(name=sweep_name, type="EMESweep", 
            property={"simulation_name": simu_name,
                    "sweep_type": "values", 
                    "parameters": [{"variable": gap, "values": [0.45, 0.55, 0.65]}],
                    "result": [{"name": "SMatrix", "component": "S", "result": "S-Matrix"}]})
swp_res = simu["EMESweep"].run()

6.6 FDTDSweep

The syntax for adding FDTDSweep solver to the project and its properties settings are as follows. When adding a FDTDSweep solver, it is assumed that global parameters, FDTD solver, source and monitor/analysis have already been added, and the pj is an instance of the project. The add function does not return any data.

simu = pj.Simulation()
simu.add(        
        name: str,
        type: Literal["FDTDSweep"],
        property: dict
    )

Simulation name

Specifies the name of the simulation solver used for parameter sweep.

sweep type

Selects the type of parameter sweep settings, with options of "ranges" and "values".

Parameters

Result

name: Specifies the name of the parameter sweep result.
result: Specifies the name of the analysis that has been added.
component: Specifies the result component to be extracted.

Example:

The following script adds a FDTDSweep solver to obtain the results of the power monitor and the mode expansion analysis, where the sweep range must be set through global parameters. This script assumes that the FDTD solver and Mode Expansion analysis have been set up.

simu_name = "FDTD_Solver"        # The name of FDTD solver
monitor_name = "Power_Monitor"   # The name of power monitor 
analysis_name = "ModeExpansion"  # The name of mode expansion analysis
sweep_name = "FDTD_Sweep"        # The name of sweep name
res1 = "T"                       # The name of the sweep result
res2 = "T_forward"               # The name of the sweep result
para = pj.GlobalParameter()
gap = para.add(name="gap", expression=0.5, description='')  # The setting of parameter sweep must use global parameters.
simu = pj.Simulation()
simu.add(name=sweep_name, type="FDTDsweep", property={
            "simulation_name": simu_name, 
            "parameters": [{"variable": gap, "number_of_points": 3, "start": 0.5, "stop": 0.6 }],
            "result": [{"name": res1, "result": monitor_name, "component": "T"},
                       {"name": res2, "result": analysis_name, "component": "T_forward"}]})
swp_res = simu["FDTDSweep"].run()

6.7 FDTDSmatrix

The syntax for adding FDTDSmatrix solver to the project and its properties settings are as follows. When adding a FDTDSmatrix solver, it is assumed that FDTD solver and FDTD port have already been added, and the pj is an instance of the project. The add function does not return any data.

simu = pj.Simulation()
simu.add(        
        name: str,
        type: "FDTDSmatrix",
        property: dict
    )

simulation_name The specified FDTD solver name| port active

Simulation name

Specifies the name of the simulation solver used for parameter sweep.

S_matrix_setup

Port: Specifies the name of port in the FDTD simulation region.
Active: Selects the enabled port as the excitation source, and the number of ""Active" port determines the number of simulation sweep.

Example:

The following script add an FDTDSmatrix solver to obtain the S matrix of the FDTD port, and enable the calculated port through "active".

simu_name = "FDTD_solver"     # the name of FDTD solver
sweep_name = "matrix_sweep"   # the name of FDTD Smatrix sweep
port1_name = "port1"          # the name of port1
port2_name = "port2"          # the name of port2
simu = pj.Simulation()
smatrix_res = simu.add(name=sweep_name, type="FDTDSmatrix",
                            property={"simulation_name": simu_name,
                                        "s_matrix_setup": [{"port": port1_name, "active": True},
                                                        {"port": port2_name, "active": True}]})

6.5 DDM

6.5.1 DDM Settings

Incorporate a DDM solver into the current project using the code type='DDM.

add(
            self,
            *,
            name: str,
            type: Literal["DDM"],
            property: OeDevicePostProcess,
    )

Example:

    simu = pj.Simulation()
    simu.add(name=simu_name, type="DDM", property={
        "background_material": mt["mat_sio2"], 
        "general": {"solver_mode": "steady_state", 
                    "norm_length": 20,
                    "temperature_dependence": "isothermal",
                    "temperature": 298.15,
                    },
        "geometry": {"dimension": "2d_x_normal", "x": 10, "x_span": 0, "y_min": 0, "y_max": 3.7, "z_min": -0.15, "z_max": 1.25},
        "mesh_settings": {"mesh_size": 0.06},
        "advanced": {"non_linear_solver": "newton",
                     "linear_solver": "mumps",
                     "fermi_statistics": "disabled", # or "enabled"
                     "damping": "potential", # or "none"
                     "potential_update": 1.0,
                     "max_iterations": 15,
                     "relative_tolerance": 1e-5,
                     "tolerance_relax": 1e5,
                     "divergence_factor": 1e25
                     }
    })

	default	type	notes
general.norm_length	1.0	float
general.solver_mode	steady_state	string	Selections are ['steady_state', 'transient'].
general.temperature_dependence	Isothermal	string	Selections are ['Isothermal'].
general.simulation_temperature	300	float
general.background_material		string
advanced.non_linear_solver	Newton	string	Selections are ['Newton'].
advanced.linear_solver	MUMPS	string
advanced.fermi_statistics	disabled	string	Selections are ['disabled', 'enabled'].
advanced.damping	none	string	Selections are ['none', 'potential'].
advanced.potential_update	1.0	float
advanced.multi_threads	let_solver_choose	string	Selections are ['let_solver_choose', 'set_thread_count'].
advanced.thread_count	4	integer
advanced.max_iterations	15	integer
advanced.relative_tolerance	1.0e-5	float
advanced.tolerance_relax	1.0e+5	float
advanced.divergence_factor	1.0e+25	float
advanced.saving on divergence	disabled	string	Selections are ['disabled', 'enabled'].
genrate.genrate_path		string
genrate.source_fraction		float
genrate.coordinate_unit	m	string	Selections are ['m', 'cm', 'um', 'nm'].
genrate.field_length_unit	m	string	Selections are ['m', 'cm', 'um', 'nm'].
geometry.dimension	2d_x_normal	string	Selections are ['2d_x_normal', '2d_y_normal', '2d_z_normal'].
geometry.x		float
geometry.x_span		float
geometry.x_min		float
geometry.x_max		float
geometry.y		float
geometry.y_span		float
geometry.y_min		float
geometry.y_max		float
geometry.z		float
geometry.z_span		float
geometry.z_min		float
geometry.z_max		float
small_signal_ac.perturbation_amplitude	0.001	float
small_signal_ac.frequency_spacing	single	string	Selections are ['single', 'linear', 'log'].
small_signal_ac.frequency	1.0e+6	float
small_signal_ac.start_frequency	1.0e+06	float
small_signal_ac.stop_frequency	1.0e+09	float
small_signal_ac.frequency_interval	9.9999e+10	float
small_signal_ac.num_frequency_points	2	integer
small_signal_ac.log_start_frequency	1.0e+06	float
small_signal_ac.log_stop_frequency	1.0e+10	float
small_signal_ac.log_num_frequency_points	2	integer

Description:

geometry：
- dimension--Set the dimension of the simulation region. Only 2D simulation is supportd currently. When it's set to "2d_x_normal", the simulation is on the yz plane. Similarly for the rest
general:
- norm_length--Set the length in the third dimension, default to be 1
- solver_mode--Set the simulation mode. Steady state, transient and SSAC simulations are supported
- temperature--Set the simulation temperature
- temperature_dependence--Set the type of the temperature dependence. Only "Isothermal" is supported currently
small_signal_ac:
- perturbation_amplitude--Set the voltage amplitude of the small signal
- frequency_spacing--Set the spacing type of the frequency
  - When it's set to "single", the frequency point is single
  - When it's set to "linear", the frequency points are uniformly sampled
  - When it's set to "log"，the frequency points are uniformly sampled base on the logarithm of frequency
- frequency--Set the value of the single frequency
- start_frequency--Set the start frequency of linear spacing
- stop_frequency--Set the stop frequency of linear spacing
- frequency_interval--Set the frequency interval of linear spacing
- num_frequency_points--Set the number of frequency points of linear spacing
- log_start_frequency--Set the start frequency of logarithmic spacing
- log_stop_frequency--Set the stop frequency of logarithmic spacing
- log_num_frequency_points--Set the number of frequency points of logarithmic spacing
advanced:
- non_linear_solver--Set the non-linear solver, only Newton method is supported currently
- linear_solver--Set the linear solver. Options are "MUMPS". MUMPS is direct linear solvers which usually give the exact solution, and supports parallel computation.
- use_quasi_fermi--Whether to directly solve for the quasi-Fermi potential instead of carrier concentration as unkowns. "enabled" means True, and "disabled" means False
- damping--Set the nonlinear update damping scheme. "potential" means the damping is based on the potential variation
- potential_update--Set the threshold potential for potential damping. The large value will reduce the strength of damping effect
- max_iterations--Set global maximum number of iterations, available when use_global_max_iterations is True
- relative_tolerance--Set the relative update tolerance
- tolerance_relax--Set the tolerance relaxation factor for convergence on relative tolerance criteria
- divergence_factor--Nonlinear solver fault with divergence when each individual function norm exceeds the threshold as its absolute tolerance multiply by this factor

6.5.2 FDTD

6.5.2.1 Setting

Incorporate an FDTD(Finite-Difference Time-Domain) solver into the current project using the code type='FDTD'.

add(
            self,
            *,
            name: str,
            type: Literal["FDTD"],
            property: FdtdPostProcess,
    )

Example:

 simu = pj.Simulation()
    simu.add(name=simu_name, type="FDTD",
             property={"background_material": mt["mat_sio2"],
                       "geometry": {"x": x_mean, "x_span": x_span, "y": y_mean, "y_span": y_span, "z": z_mean, "z_span": z_span, },
                       "general": {"simulation_time": 2000, },
                       "mesh_settings": {"mesh_factor": 1.2, "mesh_type": "auto_non_uniform",
                                         "mesh_accuracy": {"cells_per_wavelength": 14},
                                         "minimum_mesh_step_settings": {"min_mesh_step": 1e-4},
                                         "mesh_refinement": {"mesh_refinement": "curve_mesh", }},
                       "boundary_conditions": {"x_min_bc": "PML", "x_max_bc": "PML", "y_min_bc": "PML", "y_max_bc": "PML", "z_min_bc": "PML", "z_max_bc": "PML",
                                               "pml_settings": {"all_pml": {"profile":"standard","layer": 8, "kappa": 2, "sigma": 0.8, "polynomial": 3, "alpha": 0, "alpha_polynomial": 1, }}},
                       'advanced_options': {'auto_shutoff': {'auto_shutoff_min': 1.00e-4, 'down_sample_time': 200}},
                       })
    # endregion

Parameters	Default	Type	Notes
extra.fdtd_port_group.source_port		string	To extra data of source port from the result of FDTD simulation.
general.dimension	3d	string	Selections are ['3d'].
general.using_optical_path_estimate_time	false	bool
general.simulation_time	1000	integer	To set the simulation time for transient simulation.
mesh_settings.mesh_type	auto_non_uniform	string	Selections are ['auto_non_uniform', 'uniform'].
mesh_settings.mesh_accuracy.cells_per_wavelength	15	integer	Set the mesh accuracy for region of FDTD simulation.
mesh_settings.mesh_step_settings.dx	0.1	float	Set the miniimum of spacing between mesh step centers in x direction.
mesh_settings.mesh_step_settings.dy	0.1	float	Set the miniimum of spacing between mesh step centers in y direction.
mesh_settings.mesh_step_settings.dz	0.1	float	Set the miniimum of spacing between mesh step centers in z direction.
mesh_settings.minimum_mesh_step_settings.min_mesh_step	0.0001	float	Set the minimum vale of mesh step.
advanced_options.auto_shutoff.use_early_shutoff	true	bool	Decide whether to use early shutoff.
advanced_options.auto_shutoff.auto_shutoff_min	1.0e-4	float	Control the simulation shutoff based on the ratio of energy to the maximum input energy.
advanced_options.auto_shutoff.down_sample_time	100	float	Inspect the auto shutoff conditions every down sample time.
advanced_options.live_slice_filed_display_settings.show_field	false	bool	Decide whether to gennerate the electric intensity filed image for the results.
advanced_options.live_slice_filed_display_settings.select_field_section	2d_z_normal	string	Selections are ['2d_y_normal', '2d_z_normal'].
advanced_options.live_slice_filed_display_settings.select_component	ex	string	Selections are ['ex', 'ey', 'ez'].
advanced_options.live_slice_filed_display_settings.time_interval	200	float	Set the time interval for displaying image.
advanced_options.live_slice_filed_display_settings.position	0	float	Set the center position of the field image.
thread_setting.thread	4	integer	Determine the number of cores required to run the simulation on the local computer.

6.5.2.2 Boundary

The following content comprises code explanations and specific examples of boundary conditions in optical simulation.

Parameters	Description
property	The default property of the optical boundary.
pml_same_settings	To decide whether using the same pml settings on every directions or not.

As demonstrated in the following examples, we also provide support for customizing boundary conditions in different directions.

Parameters	Default	Type	Notes
general_pml.pml_same_settings	true	bool	To decide whether using the same pml settings on every directions or not.
general_pml.pml_profile	standard	string	To provide the options of PML profile.
general_pml.pml_layer	-	integer	Set the number of layers after discretizing the PML region.
general_pml.pml_kappa	-	float	Set the kappa parameter related to the absorption characteristics of the PML region.
general_pml.pml_sigma	-	float	Set the sigma parameter related to the absorption characteristics of the PML region.
general_pml.pml_polynomial	-	integer	Set the order of the kappa and the sigma parameters.
general_pml.pml_alpha	-	float	Set the alpha parameter related to the absorption characteristics of the PML region.
general_pml.pml_alpha_polynomial	-	integer	Set the order of the alpha parameter.
general_pml.pml_min_layers	-	integer	Set the minimum number of layers within a reasonable range for the PML layers.
general_pml.pml_max_layers	-	integer	Set themaximum number of layers within a reasonable range for the PML layers.
geometry.x	-	float	The x-coordinate of the center point position of the boundary.
geometry.x_span	-	float	The length in x direction of the boundary. Restrained by condition: >0.
geometry.x_min	-	float	The minimum x-coordinate endpoint data of the boundary.
geometry.x_max	-	float	The maximum x-coordinate endpoint data of the boundary.
geometry.y	-	float	The y-coordinate of the center point position of the boundary.
geometry.y_span	-	float	The width in y direction of the boundary. Restrained by condition: >0.
geometry.y_min	-	float	The minimum y-coordinate endpoint data of the boundary.
geometry.y_max	-	float	The maximum y-coordinate endpoint data of the boundary.
geometry.z	-	float	The z-coordinate of the center point position of the boundary.
geometry.z_span	-	float	The thinckness in z direction of the boundary. Restrained by condition: >0.
geometry.z_min	-	float	The z-coordinate of the bottom position of the thickness of the boundary.
geometry.z_max	-	float	The z-coordinate of the top position of the thickness of the boundary.
boundary.x_max	-	string	Set the boundary type in the x+ direction. Selections are ['PML', 'PEC', 'metal', 'PMC', 'periodic'].
boundary.x_min	-	string	Set the boundary type in the x- direction. Selections are ['PML', 'PEC', 'metal', 'PMC', 'symmetric', 'anti_symmetric', 'periodic'].
boundary.y_max	-	string	Set the boundary type in the y+ direction. Selections are ['PML', 'PEC', 'metal', 'PMC', 'periodic'].
boundary.y_min	-	string	Set the boundary type in the y- direction. Selections are ['PML', 'PEC', 'metal', 'PMC', 'symmetric', 'anti_symmetric', 'periodic'].
boundary.z_max	-	string	Set the boundary type in the z+ direction. Selections are ['PML', 'PEC', 'metal', 'PMC', 'periodic'].
boundary.z_min	-	string	Set the boundary type in the z- direction. Selections are ['PML', 'PEC', 'metal', 'PMC', 'symmetric', 'anti_symmetric', 'periodic'].

If you need to customize the boundary conditions for simulation requirements, you can also refer to the table below for modifying boundary conditions in different directions.Taking the x coordinate axis as an example, the parameters invocation is the same for the y/z coordinates.

Parameters	Default	Type	Notes
general_pml.pml_same_settings	true	bool	To decide whether using the same pml settings on every directions or not.
general_pml.x_min_bc.pml_profile	standard	string	To provide the options of PML profile in x- direction.
general_pml.x_min_bc.pml_layer	-	integer	Set the number of layers after discretizing the PML region in x- direction.
general_pml.x_min_bc.pml_kappa	-	float	Set the kappa parameter related to the absorption characteristics of the PML region in x- direction.
general_pml.x_min_bc.pml_sigma	-	float	Set the sigma parameter related to the absorption characteristics of the PML region in x- direction.
general_pml.x_min_bc.pml_polynomial	-	integer	Set the order of the kappa and the sigma parameters in x- direction.
general_pml.x_min_bc.pml_alpha	-	float	Set the alpha parameter related to the absorption characteristics of the PML region in x- direction.
general_pml.x_min_bc.pml_alpha_polynomial	-	integer	Set the order of the alpha parameter in x- direction.
general_pml.x_min_bc.pml_min_layers	-	integer	Set the minimum number of layers within a reasonable range for the PML layers in x- direction.
general_pml.x_min_bc.pml_max_layers	-	integer	Set the maximum number of layers within a reasonable range for the PML layers in x- direction.
general_pml.x_max_bc.pml_profile	standard	string	To provide the options of PML profile in x+ direction.
general_pml.x_max_bc.pml_layer	-	integer	Set the number of layers after discretizing the PML region in x+ direction.
general_pml.x_max_bc.pml_kappa	-	float	Set the kappa parameter related to the absorption characteristics of the PML region in x+ direction.
general_pml.x_max_bc.pml_sigma	-	float	Set the sigma parameter related to the absorption characteristics of the PML region in x+ direction.
general_pml.x_max_bc.pml_polynomial	-	integer	Set the order of the kappa and the sigma parameters in x+ direction.
general_pml.x_max_bc.pml_alpha	-	float	Set the alpha parameter related to the absorption characteristics of the PML region in x+ direction.
general_pml.x_max_bc.pml_alpha_polynomial	-	integer	Set the order of the alpha parameter in x+ direction.
general_pml.x_max_bc.pml_min_layers	-	integer	Set the minimum number of layers within a reasonable range for the PML layers in x+ direction.
general_pml.x_max_bc.pml_max_layers	-	integer	Set the maximum number of layers within a reasonable range for the PML layers in x+ direction.

The code provided in this section can be utilized to incorporate boundary and mesh into the current project.

6.5.3 FDE

Integrate an FDE(Finite Difference Eigenmode) solver into the current project using the code type='FDE'.

add(
            self,
            *,
            name: str,
            type: Literal["FDE"],
            property: AfdePostProcess,
    )

Example:

    simu = pj.Simulation()
    simu.add(name=simu_name, type="FDE",
             property={"background_material": mt["mat_sio2"],
                       "geometry": {"x": x_mean, "x_span": x_span, "y": y_mean, "y_span": y_span, "z": z_mean, "z_span": z_span, },
                       "boundary_conditions": {"y_min_bc": "PEC", "y_max_bc": "PEC", "z_min_bc": "PEC", "z_max_bc": "PEC",},
                       # 'mode_removal': {'threshold': 0.02},
                       # default is '2d_x_normal' ['2d_x_normal','2d_y_normal','2d_z_normal']
                       "fractional_offset_for_group_delay": 0.0001,
                       'general': {'solver_type': '2d_x_normal'},
                       "mesh_settings": {"mesh_refinement": {"mesh_refinement": "curve_mesh"}, "mesh_factor": 1.2,
                                         "global_mesh_uniform_grid": {"dy": ogrid_global_y, "dz": ogrid_global_z, },
                                         #    'minimum_mesh_step_settings': {'min_mesh_step': 1.0e-4}
                                         }})
    # endregion

Parameters	Default	Type	Notes
general.solver_type	2d_x_normal	string	Selections are ['2d_x_normal', '2d_y_normal', '2d_z_normal', 'x', 'y', 'z'].
mesh_settings.global_mesh_uniform_grid.dx	0.02	float	The global mesh step in the x direction.
mesh_settings.global_mesh_uniform_grid.dy	0.02	float	The global mesh step in the y direction.
mesh_settings.global_mesh_uniform_grid.dz	0.02	float	The global mesh step in the z direction.
mesh_settings.minimum_mesh_step_settings.min_mesh_step	0.0001	float	Set the minimum vale of mesh step.
thread_setting.thread	4	integer	Determine the number of cores required to run the simulation on the local computer.
fde_analysis.modal_analysis.mesh_structure	false	bool	Confirm whether to generate a refractive index diagram for the structure.
fde_analysis.modal_analysis.calculate_modes	false	bool	Determine whether to calculate the modes.
fde_analysis.modal_analysis.[]far_field_settings.calculate	true	bool	Determine whether to calculate the far field.
fde_analysis.modal_analysis.[]far_field_settings.mode_selection		integer	Select the mode for which far-field calculation is needed.
fde_analysis.modal_analysis.[]far_field_settings.projection_method	planar	string	Selections are ['planar'].
fde_analysis.modal_analysis.[]far_field_settings.farfield_filter	0	float	Configure this parameter to filter near field data for eliminating high frequency ripples in the results. Its value ranging from 0 to 1.
fde_analysis.modal_analysis.[]far_field_settings.material_index	1.4	float	Set the material refractive index for projection.
fde_analysis.modal_analysis.[]far_field_settings.projection_distance	4430.65	float	The distance for far-field projection calculation.
fde_analysis.modal_analysis.[]far_field_settings.points_in_x	50	float	In x direction, the number of points in the far field.
fde_analysis.modal_analysis.[]far_field_settings.points_in_y	50	float	In y direction, the number of points in the far field.
fde_analysis.modal_analysis.[]far_field_settings.farfield_x	0	float	In x direction, the position of far field center point.
fde_analysis.modal_analysis.[]far_field_settings.farfield_x_span	26.1834	float	In x direction, the span of far field range.
fde_analysis.modal_analysis.[]far_field_settings.farfield_y	0	float	In y direction, the position of far field center point.
fde_analysis.modal_analysis.[]far_field_settings.farfield_y_span	18.1231	float	In y direction, the span of far field range.
fde_analysis.modal_analysis.wavelength	1.55	float	The mode wavelength for FDE calculation.
fde_analysis.modal_analysis.wavelength_offset	0.002	float	The mode wavelength offset for FDE calculation.
fde_analysis.modal_analysis.number_of_trial_modes	5	integer	When calculating modes, determine the calculated number of modes around the refractive index.
fde_analysis.modal_analysis.search	max_index	string	Calculate the mode based on the maximum refractive index or user defined refractive index in the structure. Selections are ['near_n', 'max_index'].
fde_analysis.modal_analysis.n	1	float	Under the 'near_n' condition, use this value of refractive index to search the source mode.
fde_analysis.modal_analysis.calculate_group_index	false	bool	Determine whether to calculate the group refractive index.
fde_analysis.modal_analysis.bent_waveguide.bent_waveguide	false	bool	Select whether to calculate modes in bent waveguides.
fde_analysis.modal_analysis.bent_waveguide.radius	0.0	float	Set the waveguide radius for bent waveguides.
fde_analysis.modal_analysis.bent_waveguide.orientation	0.0	float	The bent direction of the waveguide.
fde_analysis.modal_analysis.bent_waveguide.location	simulation_center	string	Set the bent center position of bent waveguides. Selections are ['simulation_center'].
fde_analysis.modal_analysis.mode_removal.threshold	-	float	Screen the FDTD port source according to the energy arriving at the boundary to ensure the accuracy of the calculated transmission FDTD port mode.
fde_analysis.frequency_analysis.frequency_analysis	false	bool	Determine whether to invoke frequency analysis.
fde_analysis.frequency_analysis.start_wavelength	-	float	Set the start frequency of the frequency analysis.
fde_analysis.frequency_analysis.stop_wavelength	-	float	Set the stop frequency of the frequency analysis.
fde_analysis.frequency_analysis.number_of_points	10	integer	Set the number of points in the frequency analysis
fde_analysis.frequency_analysis.effective_index	1.0	float	To search the mode near this refractive index.
fde_analysis.frequency_analysis.detailed_dispersion_calculation	false	bool	Determine whether to calculate the dispersion of structure.

Simulation

6.1 FDE​

General​

Background material​

Geometry​

Mesh settings​

Boundary conditions​

Advanced​

6.2 EME​

General​

Background material​

Geometry​

EME setup​

Mesh settings​

Transverse mesh settings ​

Boundary conditions​

Advanced​

6.3 FDTD​

General​

Background material​

Geometry​

Mesh settings​

Boundary conditions​

advanced_options.​

6.4 FDESweep​

Simulation name​

sweep type​

Parameters​

Result​

6.5 EMESweep​

Simulation name​

Sweep type​

Parameters​

Result​

6.6 FDTDSweep​

Simulation name​

sweep type​

Parameters​

Result​

6.7 FDTDSmatrix​

Simulation name​

S_matrix_setup​

6.5 DDM​

6.5.1 DDM Settings​

6.5.2 FDTD​

6.5.2.1 Setting​

6.5.2.2 Boundary​

6.5.3 FDE​

6.1 FDE

General

Background material

Geometry

Mesh settings

Boundary conditions

Advanced

6.2 EME

General

Background material

Geometry

EME setup

Mesh settings

Transverse mesh settings

Boundary conditions

Advanced

6.3 FDTD

General

Background material

Geometry

Mesh settings

Boundary conditions

advanced_options.

6.4 FDESweep

Simulation name

sweep type

Parameters

Result

6.5 EMESweep

Simulation name

Sweep type

Parameters

Result

6.6 FDTDSweep

Simulation name

sweep type

Parameters

Result

6.7 FDTDSmatrix

Simulation name

S_matrix_setup

6.5 DDM

6.5.1 DDM Settings

6.5.2 FDTD

6.5.2.1 Setting

6.5.2.2 Boundary

6.5.3 FDE