Method __init__

python/adjoint/objective.py:311–343

Initialize an instance of differentiable Fourier fields instance. Args: sim: the Meep simulation object of the problem. volume: the volume over which the eigenmode coefficient is calculated. Due to an unresolved bug, the size must not be zero in at least one

(
        self,
        sim: mp.Simulation,
        volume: mp.Volume,
        component: int,
        yee_grid: Optional[bool] = False,
        decimation_factor: Optional[int] = 0,
        subtracted_dft_fields: Optional[FluxData] = None,
    )

    """A differentiable frequency-dependent Fourier fields (dft_fields)"""

    def __init__(
        self,
        sim: mp.Simulation,
        volume: mp.Volume,
        component: int,
        yee_grid: Optional[bool] = False,
        decimation_factor: Optional[int] = 0,
        subtracted_dft_fields: Optional[FluxData] = None,
    ):
        """Initialize an instance of differentiable Fourier fields instance.

        Args:
          sim: the Meep simulation object of the problem.
          volume: the volume over which the eigenmode coefficient is calculated. Due to an unresolved bug,
            the size must not be zero in at least one direction.
          component: field component (e.g. mp.Ex, mp.Hz, etc.) of the Fourier fields
          yee_grid: if True, the Fourier fields are evaluated at the corresponding Yee grid points;
            otherwise, they are interpolated fields at the center of each voxel. Default is False
          decimation_factor: An integer used to specify the number of timesteps between updates of
            the DFT fields. The default is 0, at which the value is automatically determined from the
            Nyquist rate of the bandwidth-limited sources and the DFT monitor. It can be turned off
            by setting it to 1.
          subtracted_dft_fields: the DFT fields obtained using `get_flux_data` from
            a previous normalization run. This is subtracted from the DFT fields
            of this mode monitor in order to improve the accuracy of the
            reflectance measurement (i.e., the $S_{11}$ scattering parameter). Default is None.
        """
        super().__init__(sim)
        self.volume = sim._fit_volume_to_simulation(volume)
        self.component = component
        self.yee_grid = yee_grid
        self.decimation_factor = decimation_factor
        self.subtracted_dft_fields = subtracted_dft_fields

    def register_monitors(self, frequencies):
        self._frequencies = np.asarray(frequencies)