This is a basic Tidy3D script showing the FDTD simulation of a delectric cube in the presence of a point dipole.
Before running this notebook, make sure to have:
# import packages and authenticate (if needed)
import numpy as np
import matplotlib.pylab as plt
import tidy3d as td
import tidy3d.web as web
# web.configure("YOUR API KEY GOES HERE")
# set up parameters of simulation (length scales are micrometers)
freq0 = td.C_0 / 0.75
square = td.Structure(
geometry=td.Box(center=(0, 0, 0), size=(1.5, 1.5, 1.5)),
medium=td.Medium(permittivity=2.0)
)
Create a Source. In this case it is a Point Dipole which is a uniform current source with a zero size.
# create source
source = td.PointDipole(
center=(-1.5, 0, 0),
source_time=td.GaussianPulse(freq0=freq0, fwidth=freq0 / 10.0),
polarization="Ey",
)
Create a Monitor like this FieldMonitor to record electromagnetic fields in the frequency domain for our base frequency freq0. By default, this monitor is centered at the (0,0,0) = (x,y,z) coordinate and we specify a infinite xy plane in which to record the fields through the size parameter.
# create monitor
monitor = td.FieldMonitor(
size=(td.inf, td.inf, 0),
freqs=[freq0],
name="fields",
colocate=True,
)
All these components are used to create a Simulation:
sim = td.Simulation(
size=(4, 3, 3),
grid_spec=td.GridSpec.auto(min_steps_per_wvl=25),
structures=[square],
sources=[source],
monitors=[monitor],
run_time=120/freq0,
)
# visualize in 3D
sim.plot_3d()
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 [179, 147, 147] for 3 million cells.
The python web API is used to run your simulation quickly in the cloud. The output data is stored in a SimulationData container.
# run simulation
data = td.web.run(sim, task_name="quickstart", path="data/data.hdf5", verbose=True)
[09:31:15] Created task 'quickstart' with task_id 'fdve-a65fc275-cb18-4630-adf2-0a4e976bf5fbv1'.
View task using web UI at 'https://tidy3d.simulation.cloud/workbench?taskId=fdve-a65fc275-cb18- 4630-adf2-0a4e976bf5fbv1'.
Output()
[09:31:17] status = queued
Output()
[09:31:27] status = preprocess
[09:31:32] Maximum FlexCredit cost: 0.025. Use 'web.real_cost(task_id)' to get the billed FlexCredit cost after a simulation run.
starting up solver
running solver
To cancel the simulation, use 'web.abort(task_id)' or '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.
Output()
[09:31:39] early shutoff detected, exiting.
status = postprocess
Output()
[09:31:44] status = success
[09:31:45] View simulation result at 'https://tidy3d.simulation.cloud/workbench?taskId=fdve-a65fc275-cb18- 4630-adf2-0a4e976bf5fbv1'.
Output()
[09:31:46] loading SimulationData from data/data.hdf5
# see the log
print(data.log)
Simulation domain Nx, Ny, Nz: [179, 147, 147] Applied symmetries: (0, 0, 0) Number of computational grid points: 4.0184e+06. Using subpixel averaging: True Number of time steps: 7.5140e+03 Automatic shutoff factor: 1.00e-05 Time step (s): 3.9959e-17 Compute source modes time (s): 0.0422 Compute monitor modes time (s): 0.0026 Rest of setup time (s): 2.1802 Running solver for 7514 time steps... - Time step 300 / time 1.20e-14s ( 4 % done), field decay: 1.00e+00 - Time step 498 / time 1.99e-14s ( 6 % done), field decay: 1.00e+00 - Time step 601 / time 2.40e-14s ( 8 % done), field decay: 2.60e-01 - Time step 901 / time 3.60e-14s ( 12 % done), field decay: 2.62e-03 - Time step 1202 / time 4.80e-14s ( 16 % done), field decay: 6.38e-05 - Time step 1502 / time 6.00e-14s ( 20 % done), field decay: 2.22e-06 Field decay smaller than shutoff factor, exiting solver. Solver time (s): 1.2144 Data write time (s): 0.0036
This monitor data can be easily plotted through available plot methods. You can also save, modify, and custom plot the raw FieldData and more.
# plot the field data stored in the monitor
ax = data.plot_field("fields", "Ey", z=0)
See all our examples to help you with your own designs!
