Basic simulation template#

This is a basic Tidy3D script showing the FDTD simulation of a delectric cube in the presence of a point dipole.

[1]:

import numpy as np

# import the package and the web API
import tidy3d as td
import tidy3d.web as web

[2]:

# set up parameters of simulation (length scales are micrometers)
grid_cells_per_wvl = 30
pml = td.PML()
sim_size = (4, 4, 4)
lambda0 = 1.0
freq0 = td.C_0 / lambda0
fwidth = freq0 / 10.0
run_time = 12.0 / fwidth

# create structure
dielectric = td.Medium.from_nk(n=2, k=0, freq=freq0)
square = td.Structure(
    geometry=td.Box(center=(0, 0, 0), size=(1.5, 1.5, 1.5)), medium=dielectric
)

# create source
source = td.UniformCurrentSource(
    center=(-1.5, 0, 0),
    size=(0, 0.4, 0.4),
    source_time=td.GaussianPulse(freq0=freq0, fwidth=fwidth),
    polarization="Ey",
)

# create monitor
monitor = td.FieldMonitor(
    fields=["Ex", "Ey", "Hz"],
    center=(0, 0, 0),
    size=(td.inf, td.inf, 0),
    freqs=[freq0],
    name="fields_on_plane",
)

# Initialize simulation
sim = td.Simulation(
    size=sim_size,
    grid_spec=td.GridSpec.auto(min_steps_per_wvl=grid_cells_per_wvl),
    structures=[square],
    sources=[source],
    monitors=[monitor],
    run_time=run_time,
    boundary_spec=td.BoundarySpec.all_sides(boundary=td.PML()),
)

[16:44:57] WARNING: Default value for the field monitor           monitor.py:261
           'colocate' setting has changed to 'True' in Tidy3D                   
           2.4.0. All field components will be colocated to the                 
           grid boundaries. Set to 'False' to get the raw fields                
           on the Yee grid instead.

[3]:

print(
    f"simulation grid is shaped {sim.grid.num_cells} for {int(np.prod(sim.grid.num_cells)/1e6)} million cells."
)

simulation grid is shaped [192, 192, 192] for 7 million cells.

[4]:

# run the simulation, download the data.
data = web.run(sim, task_name="quickstart", path="data/data.hdf5", verbose=True)

           Created task 'quickstart' with task_id                  webapi.py:188
           'fdve-1f7261fd-4206-4e7d-b83c-a8bafda8ceb3v1'.

           View task using web UI at                               webapi.py:190
           'https://tidy3d.simulation.cloud/workbench?taskId=fdve-              
           1f7261fd-4206-4e7d-b83c-a8bafda8ceb3v1'.

[16:44:59] status = queued                                         webapi.py:361

[16:45:07] status = preprocess                                     webapi.py:355

[16:45:11] Maximum FlexCredit cost: 0.028. Use                     webapi.py:341
           'web.real_cost(task_id)' to get the billed FlexCredit                
           cost after a simulation run.

           starting up solver                                      webapi.py:377

[16:45:12] running solver                                          webapi.py:386

           To cancel the simulation, use 'web.abort(task_id)' or   webapi.py:387
           'web.delete(task_id)' or abort/delete the task in the                
           web UI. Terminating the Python script will not stop the              
           job running on the cloud.

[16:45:33] early shutoff detected, exiting.                        webapi.py:404

           status = postprocess                                    webapi.py:419

[16:45:37] status = success                                        webapi.py:426

[16:45:39] loading SimulationData from data/data.hdf5              webapi.py:590

[5]:

# see the log
print(data.log)

Simulation domain Nx, Ny, Nz: [192, 192, 192]
Applied symmetries: (0, 0, 0)
Number of computational grid points: 7.3014e+06.
Using subpixel averaging: True
Number of time steps: 1.2659e+04
Automatic shutoff factor: 1.00e-05
Time step (s): 3.1624e-17


Compute source modes time (s):     0.0164
Compute monitor modes time (s):    0.0023
Rest of setup time (s):            3.2458

Running solver for 12659 time steps...
- Time step    506 / time 1.60e-14s (  4 % done), field decay: 1.00e+00
- Time step    839 / time 2.65e-14s (  6 % done), field decay: 1.00e+00
- Time step   1012 / time 3.20e-14s (  8 % done), field decay: 1.00e+00
- Time step   1519 / time 4.80e-14s ( 12 % done), field decay: 1.44e-01
- Time step   2025 / time 6.40e-14s ( 16 % done), field decay: 3.24e-02
- Time step   2531 / time 8.00e-14s ( 20 % done), field decay: 1.38e-02
- Time step   3038 / time 9.61e-14s ( 24 % done), field decay: 6.96e-03
- Time step   3544 / time 1.12e-13s ( 28 % done), field decay: 3.33e-03
- Time step   4050 / time 1.28e-13s ( 32 % done), field decay: 2.39e-03
- Time step   4557 / time 1.44e-13s ( 36 % done), field decay: 1.64e-03
- Time step   5063 / time 1.60e-13s ( 40 % done), field decay: 1.21e-03
- Time step   5569 / time 1.76e-13s ( 44 % done), field decay: 7.31e-04
- Time step   6076 / time 1.92e-13s ( 48 % done), field decay: 5.03e-04
- Time step   6582 / time 2.08e-13s ( 52 % done), field decay: 2.34e-04
- Time step   7089 / time 2.24e-13s ( 56 % done), field decay: 1.58e-04
- Time step   7595 / time 2.40e-13s ( 60 % done), field decay: 6.85e-05
- Time step   8101 / time 2.56e-13s ( 64 % done), field decay: 7.63e-05
- Time step   8608 / time 2.72e-13s ( 68 % done), field decay: 4.45e-05
- Time step   9114 / time 2.88e-13s ( 72 % done), field decay: 6.23e-05
- Time step   9620 / time 3.04e-13s ( 76 % done), field decay: 2.68e-05
- Time step  10127 / time 3.20e-13s ( 80 % done), field decay: 3.22e-05
- Time step  10633 / time 3.36e-13s ( 84 % done), field decay: 1.45e-05
- Time step  11139 / time 3.52e-13s ( 88 % done), field decay: 2.10e-05
- Time step  11646 / time 3.68e-13s ( 92 % done), field decay: 5.99e-06
Field decay smaller than shutoff factor, exiting solver.

Solver time (s):                   16.2442
Data write time (s):               0.0038

[6]:

# plot the fields stored in the monitor
ax = data.plot_field("fields_on_plane", "Ey", z=0)
_ = ax.set_title("Ey(x,y)")

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