# tidy3d.AstigmaticGaussianBeam#

class AstigmaticGaussianBeam[source]#

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:
• name (Optional[str] = None) β Optional name for the source.

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

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

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

• num_freqs (ConstrainedIntValue = 1) β 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['+', '-']) β Specifies propagation in the positive or negative direction of the injection axis.

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

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

• pol_angle (float = 0) β [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)) β [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)) β [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:

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

Methods

Inherited Common Usage

waist_sizes#
waist_distances#
__hash__()#

Hash method.