Class FluxRegion

python/simulation.py:510–564

A `FluxRegion` object is used with [`add_flux`](#flux-spectra) to specify a region in which Meep should accumulate the appropriate Fourier-transformed fields in order to compute a flux spectrum. It represents a region (volume, plane, line, or point) in which to compute the integral

class FluxRegion:
    """
    A `FluxRegion` object is used with [`add_flux`](#flux-spectra) to specify a region in
    which Meep should accumulate the appropriate Fourier-transformed fields in order to
    compute a flux spectrum. It represents a region (volume, plane, line, or point) in
    which to compute the integral of the Poynting vector of the Fourier-transformed
    fields. `ModeRegion` is an alias for `FluxRegion` for use with `add_mode_monitor`.

    Note that the flux is always computed in the *positive* coordinate direction, although
    this can effectively be flipped by using a `weight` of -1.0. This is useful, for
    example, if you want to compute the outward flux through a box, so that the sides of
    the box add instead of subtract.
    """

    def __init__(
        self,
        center: Vector3Type = None,
        size: Vector3Type = Vector3(),
        direction: int = mp.AUTOMATIC,
        weight: float = 1.0,
        volume: Optional[Volume] = None,
    ):
        """
        Construct a `FluxRegion` object.

        + **`center` [ `Vector3` ]** — The center of the flux region (no default).

        + **`size` [ `Vector3` ]** — The size of the flux region along each of the coordinate
          axes. Default is `(0,0,0)`; a single point.

        + **`direction` [ `direction` constant ]** — The direction in which to compute the
          flux (e.g. `mp.X`, `mp.Y`, etcetera). Default is `AUTOMATIC`, in which the
          direction is determined by taking the normal direction if the flux region is a
          plane (or a line, in 2d). If the normal direction is ambiguous (e.g. for a point
          or volume), then you *must* specify the `direction` explicitly (not doing so
          will lead to an error).

        + **`weight` [ `complex` ]** — A weight factor to multiply the flux by when it is
          computed. Default is 1.0.

        + **`volume` [ `Volume` ]** — A `meep.Volume` can be used to specify the flux region
          instead of a `center` and a `size`.
        """
        if center is None and volume is None:
            raise ValueError("Either center or volume required")

        if volume:
            self.center = volume.center
            self.size = volume.size
        else:
            self.center = Vector3(*center)
            self.size = Vector3(*size)

        self.direction = direction
        self.weight = complex(weight)


ModeRegion = FluxRegion