flex_rf.tidy3d.DiffractionData

Type: class │ Base(s): AbstractFieldProjectionData

Description

Data for a DiffractionMonitor: complex components of diffracted far fields.

Notes

The diffraction data are separated into S and P polarizations. At normal incidence when S and P are undefined, P(S) corresponds to Ey(Ez) polarization for monitor normal to x, P(S) corresponds to Ex(Ez) polarization for monitor normal to y, and P(S) corresponds to Ex(Ey) polarization for monitor normal to z.

The power amplitudes per polarization and diffraction order, and correspondingly the power per diffraction order, correspond to the power carried by each diffraction order in the monitor normal direction. They are not to be confused with power carried by plane waves in the propagation direction of each diffraction order, which can be obtained from the spherical-coordinate fields which are also stored. The power definition is such that the grating efficiency is the recorded power over the input source power, and the direct sum over the power in all orders should equal the total power flowing through the monitor.

Example(s)

from tidy3d import DiffractionDataArray
f = np.linspace(1e14, 2e14, 10)
orders_x = list(range(-4, 5))
orders_y = list(range(-6, 7))
pol = ["s", "p"]
coords = dict(orders_x=orders_x, orders_y=orders_y, f=f)
values = (1+1j) * np.random.random((len(orders_x), len(orders_y), len(f)))
field = DiffractionDataArray(values, coords=coords)
monitor = DiffractionMonitor(
    center=(1,2,3), size=(np.inf,np.inf,0), freqs=f, name='diffraction'
)
data = DiffractionData(
    monitor=monitor, sim_size=[1,1], bloch_vecs=[1,2],
    Etheta=field, Ephi=field, Er=field,
    Htheta=field, Hphi=field, Hr=field,
)

Parameters

monitor [DiffractionMonitor]

Diffraction monitor associated with the data.

Er [DiffractionDataArray]

Spatial distribution of r-component of the electric field.

Etheta [DiffractionDataArray]

Spatial distribution of the theta-component of the electric field.

Ephi [DiffractionDataArray]

Spatial distribution of phi-component of the electric field.

Hr [DiffractionDataArray]

Spatial distribution of r-component of the magnetic field.

Htheta [DiffractionDataArray]

Spatial distribution of theta-component of the magnetic field.

Hphi [DiffractionDataArray]

Spatial distribution of phi-component of the magnetic field.

sim_size [tuple[float, float]]

Size of the near field in the local x and y directions.

bloch_vecs [tuple[float, float] | tuple[ArrayFloat1D, ArrayFloat1D]]

Bloch vectors along the local x and y directions in units of 2 * pi / (simulation size along the respective dimension).

medium [MediumType] = factory: Medium

Background medium through which to project fields.

is_2d_simulation [bool] = False

Indicates whether the monitor data is for a 2D simulation.

Attributes

amps [DataArray]

Complex power amplitude in each order for ‘s’ and ‘p’ polarizations, normalized so that the power carried by the wave of that order and polarization equals abs(amps)^2.

angles [tuple[DataArray]]

The (theta, phi) angles corresponding to each allowed pair of diffraction orders storeds as data arrays. Disallowed angles are set to np.nan.

coords_spherical [dict[str, np.ndarray]]

Coordinates grid for the fields in the spherical system.

fields_cartesian [xr.Dataset]

Get all field components in Cartesian coordinates relative to the monitor’s local origin for all allowed diffraction orders and frequencies specified in the DiffractionMonitor.

fields_spherical [xr.Dataset]

Get all field components in spherical coordinates relative to the monitor’s local origin for all allowed diffraction orders and frequencies specified in the DiffractionMonitor.

orders_x [np.ndarray]

Allowed orders along x.

orders_y [np.ndarray]

Allowed orders along y.

power [DataArray]

Total power in each order, summed over both polarizations.

radar_cross_section [DataArray]

Radar cross section in units of incident power.

reciprocal_vectors [tuple[np.ndarray, np.ndarray]]

Get the normalized “ux” and “uy” reciprocal vectors.

ux [np.ndarray]

Normalized wave vector along x relative to local_origin and oriented with respect to monitor.normal_dir, normalized by the wave number in the projection medium.

uy [np.ndarray]

Normalized wave vector along y relative to local_origin and oriented with respect to monitor.normal_dir, normalized by the wave number in the projection medium.

Methods

adjoint_source_amp(amp: DataArray, fwidth: float)

Generate an adjoint PlaneWave for a single amplitude.

compute_angles(reciprocal_vectors: tuple[np.ndarray, np.ndarray])

Compute the polar and azimuth angles associated with the given reciprocal vectors.

reciprocal_coords(orders: np.ndarray, size: float, bloch_vec: float | np.ndarray, f: float, medium: MediumType)

Get the normalized “u” reciprocal coords for a vector of orders, size, and bloch vec.

shifted_orders(orders: tuple[int, ...], bloch_vec: float | np.ndarray)

Diffraction orders shifted by the Bloch vector.