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variable distance between injection source and monitor #327

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merged 2 commits into from
Apr 22, 2022
Merged

variable distance between injection source and monitor #327

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e330736
variable distance between injection source and monitor
tylerflex Apr 19, 2022
0d159f3
shift port not source, use local grid for shift dist, reorg sims crea…
tylerflex Apr 22, 2022
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25 changes: 15 additions & 10 deletions tidy3d/plugins/smatrix/smatrix.py
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Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,7 @@
import pydantic as pd
import numpy as np

from ...constants import HERTZ, C_0
from ...constants import HERTZ, C_0, MICROMETER
from ...components.simulation import Simulation
from ...components.geometry import Box
from ...components.mode import ModeSpec
Expand All @@ -28,7 +28,7 @@ class Port(Box):

direction: Direction = pd.Field(
...,
title="Direction",
title="SHIFT_VALUEDirection",
description="'+' or '-', defining which direction is considered 'input'.",
)
mode_spec: ModeSpec = pd.Field(
Expand Down Expand Up @@ -93,6 +93,15 @@ class ComponentModeler(Tidy3dBaseModel):
description="Batch Data of task used to compute S matrix. Set internally.",
)

shift_value: pd.PositiveFloat = pd.Field(
0.1,
title="Shift Value",
description="Distance between the source and monitor of a given port. "
"Should be greater than one grid cell for best results, while being "
"small enough that the waveguide cross section does not change within the distance.",
units=MICROMETER,
)

@pd.validator("simulation", always=True)
def _sim_has_no_sources(cls, val):
"""Make sure simulation has no sources as they interfere with tool."""
Expand Down Expand Up @@ -136,18 +145,14 @@ def plot_sim(self, x: float = None, y: float = None, z: float = None, ax: Ax = N
sim_plot.sources.append(mode_source_0)
return sim_plot.plot(x=x, y=y, z=z, ax=ax)

def _shift_value(self, port: Port) -> float:
def _shift_value_signed(self, port: Port) -> float:
"""How far (signed) to shift the monitor from the source."""
normal_index = port.size.index(0.0)
dl = self.simulation.grid_size[normal_index]
if not isinstance(dl, float):
raise NotImplementedError("doesn't support nonuniform. How many grid cells to shift?")
return dl if port.direction == "+" else -1 * dl
return self.shift_value if port.direction == "+" else -1 * self.shift_value

def _shift_port(self, port: Port) -> Port:
"""Generate a new port shifted by one grid cell in normal direction."""

shift_value = self._shift_value(port)
shift_value = self._shift_value_signed(port)
center_shifted = list(port.center)
center_shifted[port.size.index(0.0)] += shift_value
port_shifted = port.copy(deep=True)
Expand Down Expand Up @@ -203,7 +208,7 @@ def _normalization_factor(self, port_source: Port, sim_data: SimulationData) ->

k0 = 2 * np.pi * C_0 / self.freq
k_eff = k0 * normalize_n_eff
shift_value = self._shift_value(port_source)
shift_value = self._shift_value_signed(port_source)
return normalize_amp * np.exp(1j * k_eff * shift_value)

def _construct_smatrix(self, batch_data: "BatchData") -> SMatrixType:
Expand Down