tidy3d.AstigmaticGaussianBeam

class AstigmaticGaussianBeam

Bases: AngledFieldSource, PlanarSource, BroadbandSource

The simple astigmatic Gaussian distribution allows both an elliptical intensity profile and different waist locations for the two principal axes of the ellipse. When equal waist sizes and equal waist distances are specified in the two directions, this source becomes equivalent to GaussianBeam.

Parameters:

• attrs (dict = {}) – Dictionary storing arbitrary metadata for a Tidy3D object. This dictionary can be freely used by the user for storing data without affecting the operation of Tidy3D as it is not used internally. Note that, unlike regular Tidy3D fields, attrs are mutable. For example, the following is allowed for setting an attr obj.attrs['foo'] = bar. Also note that Tidy3D` will raise a TypeError if attrs contain objects that can not be serialized. One can check if attrs are serializable by calling obj.json().

• name (Optional[str] = None) – Optional name for the source.

• center (Tuple[float, float, float] = (0.0, 0.0, 0.0)) – [units = um]. Center of object in x, y, and z.

• size (Tuple[NonNegativeFloat, NonNegativeFloat, NonNegativeFloat]) – [units = um]. Size in x, y, and z directions.

• source_time (Union[GaussianPulse, ContinuousWave, CustomSourceTime]) – Specification of the source time-dependence.

• num_freqs (ConstrainedIntValue = 1) – Number of points used to approximate the frequency dependence of injected field. A Chebyshev interpolation is used, thus, only a small number of points, i.e., less than 20, is typically sufficient to obtain converged results.

• direction (Literal['+', '-']) – Specifies propagation in the positive or negative direction of the injection axis.

• angle_theta (float = 0.0) – [units = rad]. Polar angle of the propagation axis from the injection axis.

• angle_phi (float = 0.0) – [units = rad]. Azimuth angle of the propagation axis in the plane orthogonal to the injection axis.

• pol_angle (float = 0) – [units = rad]. Specifies the angle between the electric field polarization of the source and the plane defined by the injection axis and the propagation axis (rad). pol_angle=0 (default) specifies P polarization, while pol_angle=np.pi/2 specifies S polarization. At normal incidence when S and P are undefined, pol_angle=0 defines: - Ey polarization for propagation along x.- Ex polarization for propagation along y.- Ex polarization for propagation along z.

• waist_sizes (Tuple[PositiveFloat, PositiveFloat] = (1.0, 1.0)) – [units = um]. Size of the beam at the waist in the local x and y directions.

• waist_distances (Tuple[float, float] = (0.0, 0.0)) – [units = um]. Distance to the beam waist along the propagation direction for the waist sizes in the local x and y directions. When direction is + and waist_distances are positive, the waist is on the - side (behind) the source plane. When direction is + and waist_distances are negative, the waist is on the + side (in front) of the source plane.

Notes

This class implements the simple astigmatic Gaussian beam described in [1].

References:

[1]

Kochkina et al., Applied Optics, vol. 52, issue 24, 2013.

Example

>>> pulse = GaussianPulse(freq0=200e12, fwidth=20e12)
>>> gauss = AstigmaticGaussianBeam(
...     size=(0,3,3),
...     source_time=pulse,
...     pol_angle=np.pi / 2,
...     direction='+',
...     waist_sizes=(1.0, 2.0),
...     waist_distances = (3.0, 4.0))

Attributes

attrs

Methods

Inherited Common Usage

waist_sizes

waist_distances

__hash__()

Hash method.