Class Source

python/source.py:18–161

The `Source` class is used to specify the current sources via the `Simulation.sources` attribute. Note that all sources in Meep are separable in time and space, i.e. of the form $\\mathbf{J}(\\mathbf{x},t) = \\mathbf{A}(\\mathbf{x}) \\cdot f(t)$ for some functions $\\mathbf{A}$ and

class Source:
    """
    The `Source` class is used to specify the current sources via the `Simulation.sources`
    attribute. Note that all sources in Meep are separable in time and space, i.e. of the
    form $\\mathbf{J}(\\mathbf{x},t) = \\mathbf{A}(\\mathbf{x}) \\cdot f(t)$ for some functions
    $\\mathbf{A}$ and $f$. Non-separable sources can be simulated, however, by modifying
    the sources after each time step. When real fields are being used (which is the
    default in many cases; see `Simulation.force_complex_fields`), only the real part of
    the current source is used.

    **Important note**: These are *current* sources (**J** terms in Maxwell's equations),
    even though they are labelled by electric/magnetic field components. They do *not*
    specify a particular electric/magnetic field which would be what is called a "hard"
    source in the FDTD literature. There is no fixed relationship between the current
    source and the resulting field amplitudes; it depends on the surrounding geometry, as
    described in the
    [FAQ](FAQ.md#how-does-the-current-amplitude-relate-to-the-resulting-field-amplitude)
    and in Section 4.4 ("Currents and Fields: The Local Density of States") in [Chapter
    4](http://arxiv.org/abs/arXiv:1301.5366) ("Electromagnetic Wave Source Conditions") of
    the book [Advances in FDTD Computational Electrodynamics: Photonics and
    Nanotechnology](https://www.amazon.com/Advances-FDTD-Computational-Electrodynamics-Nanotechnology/dp/1608071707).
    """

    def __init__(
        self,
        src,
        component,
        center=None,
        volume=None,
        size=Vector3(),
        amplitude=1.0,
        amp_func=None,
        amp_func_file="",
        amp_data=None,
    ):
        """
        Construct a `Source`.

        + **`src` [`SourceTime` class ]** — Specify the time-dependence of the source (see
          below). No default.

        + **`component` [`component` constant ]** — Specify the direction and type of the
          current component: e.g. `mp.Ex`, `mp.Ey`, etcetera for an electric-charge
          current, and `mp.Hx`, `mp.Hy`, etcetera for a magnetic-charge current. Note that
          currents pointing in an arbitrary direction are specified simply as multiple
          current sources with the appropriate amplitudes for each component. No default.

        + **`center` [`Vector3`]** — The location of the center of the current source in
          the cell. No default.

        + **`size` [`Vector3`]** — The size of the current distribution along each
          direction of the cell. Default is `(0,0,0)`: a point-dipole source.

        + **`volume` [`Volume`]** — A `meep.Volume` can be used to specify the source
          region instead of a `center` and a `size`.

        + **`amplitude` [`complex`]** — An overall complex amplitude multiplying the
          current source. Default is 1.0. Note that specifying a complex `amplitude`