FXC-4927 enable source differentiation

CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 - Added `warn_once` option to logging configuration (`td.config.logging.warn_once`) that causes each unique warning message to be shown only once per process, reducing noise from repeated validation warnings.
+- Adjoint gradients for `CustomCurrentSource.current_dataset` and `CustomFieldSource.field_dataset`.
 
 ### Changed
 - Unified inside/outside permittivity handling for all geometries when computing shape gradients.

tests/test_components/autograd/numerical/test_autograd_source_numerical.py

@@ -0,0 +1,325 @@
+from __future__ import annotations
+
+import sys
+from collections.abc import Mapping, Sequence
+from dataclasses import dataclass
+from typing import Callable
+
+import autograd as ag
+import autograd.numpy as anp
+import numpy as np
+import pytest
+
+import tidy3d as td
+import tidy3d.web as web
+
+
+@pytest.fixture(autouse=True)
+def _enable_local_cache(monkeypatch):
+    monkeypatch.setattr(td.config.local_cache, "enabled", True)
+
+
+WVL0 = 1
+FREQ0 = td.C_0 / WVL0
+FWIDTH = FREQ0 / 10
+PULSE = td.GaussianPulse(freq0=FREQ0, fwidth=FWIDTH)
+SIM_SIZE = (3 * WVL0, 3 * WVL0, 3 * WVL0)
+MONITOR_CENTER = (-0.3, 0.1, 0.2)
+MONITOR_SIZE = (0.5, 0.5, 0)
+SOURCE_SIZE = (1, 1, 0.1)
+SOURCE_CENTER = (0.1, 0.4, -0.2)
+DATASET_SPACING = 0.1
+
+
+def _axis_coords(size: float, spacing: float) -> np.ndarray:
+    """Return 1D coords for an axis; if size==0, return a single point at 0."""
+    if size <= 0:
+        return np.array([0.0])
+    # Prefer rounding to avoid silent off-by-one due to float -> int truncation
+    n = max(2, int(np.round(size / spacing)))
+    return np.linspace(-size / 2, size / 2, n)
+
+
+def _make_coords(
+    size_xyz: tuple[float, float, float], spacing: float, freq0: float
+) -> dict[str, object]:
+    x = _axis_coords(size_xyz[0], spacing)
+    y = _axis_coords(size_xyz[1], spacing)
+    z = _axis_coords(size_xyz[2], spacing)
+    return {"x": x, "y": y, "z": z, "f": [freq0]}
+
+
+def _make_field_data(
+    amp: float,
+    shape: tuple[int, int, int, int],
+    *,
+    add_noise: bool,
+    noise_scale: float = 1.0,
+    seed: int = 12345,
+) -> np.ndarray:
+    """Uniform field with optional deterministic Gaussian noise."""
+    base = amp * np.ones(shape, dtype=float)
+    if not add_noise:
+        return base
+    rng = np.random.RandomState(seed)
+    noise = rng.normal(size=shape)
+    return base + noise_scale * noise
+
+
+def _make_field_dataset_from_amplitudes(
+    amplitudes: Sequence[float],
+    field_prefix: str,
+    coords: Mapping[str, object],
+    *,
+    add_noise: bool,
+    noise_scale: float = 1.0,
+    noise_seed: int = 12345,
+) -> td.FieldDataset:
+    x = np.asarray(coords["x"])
+    y = np.asarray(coords["y"])
+    z = np.asarray(coords["z"])
+    shape = (len(x), len(y), len(z), 1)
+
+    field_components = {}
+    for amp, axis in zip(amplitudes, "xyz"):
+        data = _make_field_data(
+            amp,
+            shape,
+            add_noise=add_noise,
+            noise_scale=noise_scale,
+            seed=noise_seed,
+        )
+        field_components[f"{field_prefix}{axis}"] = td.ScalarFieldDataArray(data, coords=coords)
+
+    return td.FieldDataset(**field_components)
+
+
+def _make_custom_field_source_components(
+    amplitudes: Sequence[float],
+    field_prefix: str,
+    *,
+    add_noise: bool,
+) -> td.CustomFieldSource:
+    coords = _make_coords((SOURCE_SIZE[0], SOURCE_SIZE[1], 0.0), DATASET_SPACING, FREQ0)
+    field_dataset = _make_field_dataset_from_amplitudes(
+        amplitudes,
+        field_prefix,
+        coords,
+        add_noise=add_noise,
+        noise_scale=1.0,
+        noise_seed=12345,
+    )
+    return td.CustomFieldSource(
+        center=SOURCE_CENTER,
+        size=(SOURCE_SIZE[0], SOURCE_SIZE[1], 0.0),
+        source_time=PULSE,
+        field_dataset=field_dataset,
+    )
+
+
+def _make_custom_current_source_components(
+    amplitudes: Sequence[float],
+    field_prefix: str,
+    *,
+    add_noise: bool,
+) -> td.CustomCurrentSource:
+    coords = _make_coords(SOURCE_SIZE, DATASET_SPACING, FREQ0)
+    field_dataset = _make_field_dataset_from_amplitudes(
+        amplitudes,
+        field_prefix,
+        coords,
+        add_noise=add_noise,
+        noise_scale=1.0,
+        noise_seed=12345,
+    )
+    return td.CustomCurrentSource(
+        center=SOURCE_CENTER,
+        size=SOURCE_SIZE,
+        source_time=PULSE,
+        current_dataset=field_dataset,
+    )
+
+
+def angled_overlap_deg(v1, v2):
+    norm_v1 = np.linalg.norm(v1)
+    norm_v2 = np.linalg.norm(v2)
+
+    if np.isclose(norm_v1, 0.0) or np.isclose(norm_v2, 0.0):
+        if not (np.isclose(norm_v1, 0.0) and np.isclose(norm_v2, 0.0)):
+            return np.inf
+
+        return 0.0
+
+    dot = np.minimum(1.0, np.sum((v1 / np.linalg.norm(v1)) * (v2 / np.linalg.norm(v2))))
+    angle_deg = np.arccos(dot) * 180.0 / np.pi
+
+    return angle_deg
+
+
+def _make_sim(source: td.Source) -> td.Simulation:
+    monitor = td.FieldMonitor(
+        name="field_monitor",
+        center=MONITOR_CENTER,
+        size=MONITOR_SIZE,
+        freqs=[FREQ0],
+    )
+    return td.Simulation(
+        size=SIM_SIZE,
+        run_time=1e-12,
+        grid_spec=td.GridSpec.auto(min_steps_per_wvl=40, wavelength=WVL0),
+        sources=[source],
+        monitors=[monitor],
+        boundary_spec=td.BoundarySpec.all_sides(boundary=td.PML()),
+    )
+
+
+def _eval_objective(sim_data: td.SimulationData, field_component: str) -> float:
+    field_data = sim_data.load_field_monitor("field_monitor")
+    component = getattr(field_data, field_component, None)
+    if component is None:
+        return 0.0
+    indexers = {}
+    for dim in ("x", "y", "z", "f"):
+        if dim in component.dims:
+            indexers[dim] = component.sizes[dim] // 2
+    field_value = component.isel(**indexers).values
+    return anp.abs(field_value) ** 2
+
+
+def _eval_objective_components(
+    sim_data: td.SimulationData, field_components: Sequence[str]
+) -> float:
+    total = 0.0
+    for component in field_components:
+        total += _eval_objective(sim_data, component)
+    return total
+
+
+@dataclass(frozen=True)
+class SourceCase:
+    name: str
+    monitor_components: tuple[str, str, str]
+    delta: float
+    make_source: Callable
+
+
+VECTOR_SOURCE_CASES = [
+    # ------------------
+    # custom field source
+    # ------------------
+    SourceCase(
+        name="custom_field_vec_e",
+        monitor_components=("Ex", "Ey", "Ez"),
+        delta=1e-4,
+        make_source=lambda amps, *, add_noise: _make_custom_field_source_components(
+            amps, "E", add_noise=add_noise
+        ),
+    ),
+    SourceCase(
+        name="custom_field_vec_h",
+        monitor_components=("Hx", "Hy", "Hz"),
+        delta=1e-4,
+        make_source=lambda amps, *, add_noise: _make_custom_field_source_components(
+            amps, "H", add_noise=add_noise
+        ),
+    ),
+    # ------------------
+    # custom current source
+    # ------------------
+    SourceCase(
+        name="custom_current_vec_e",
+        monitor_components=("Ex", "Ey", "Ez"),
+        delta=1e-4,
+        make_source=lambda amps, *, add_noise: _make_custom_current_source_components(
+            amps, "E", add_noise=add_noise
+        ),
+    ),
+    SourceCase(
+        name="custom_current_vec_h",
+        monitor_components=("Hx", "Hy", "Hz"),
+        delta=1e-4,
+        make_source=lambda amps, *, add_noise: _make_custom_current_source_components(
+            amps, "H", add_noise=add_noise
+        ),
+    ),
+]
+PARAM_VECTORS = [
+    pytest.param((1.0, -0.5, 0.25), id="p1"),
+    pytest.param((0.2, 0.7, -0.9), id="p2"),
+]
+
+NOISE_CASES = [
+    pytest.param(False, id="no_noise"),
+    pytest.param(True, id="noise"),
+]
+
+
+@pytest.mark.numerical
+@pytest.mark.parametrize("params", PARAM_VECTORS)
+@pytest.mark.parametrize("add_noise", NOISE_CASES)
+@pytest.mark.parametrize("case", VECTOR_SOURCE_CASES, ids=lambda case: case.name)
+def test_custom_source_gradients(
+    _enable_local_cache,
+    tmp_path,
+    case,
+    params,
+    add_noise,
+):
+    delta = case.delta
+    monitor_components = case.monitor_components
+    label = f"{case.name}_{'noise' if add_noise else 'clean'}_{params!r}"
+
+    make_source = lambda amps: case.make_source(amps, add_noise=add_noise)
+
+    def objective_adj(ax, ay, az):
+        sim = _make_sim(make_source((ax, ay, az)))
+        sim_data = web.run(
+            sim,
+            task_name=f"{label}_adj",
+            path=tmp_path / f"{label}_adj.hdf5",
+            local_gradient=True,
+            verbose=False,
+        )
+        return _eval_objective_components(sim_data, monitor_components)
+
+    grad_adjoint = np.array(
+        [
+            ag.grad(objective_adj, 0)(*params),
+            ag.grad(objective_adj, 1)(*params),
+            ag.grad(objective_adj, 2)(*params),
+        ],
+        dtype=float,
+    )
+
+    sims = {}
+    for idx, axis in enumerate("xyz"):
+        params_plus = list(params)
+        params_plus[idx] += delta
+        params_minus = list(params)
+        params_minus[idx] -= delta
+        sims[f"{label}_fd_{axis}_plus"] = _make_sim(make_source(tuple(params_plus)))
+        sims[f"{label}_fd_{axis}_minus"] = _make_sim(make_source(tuple(params_minus)))
+
+    sim_data_map = web.run_async(
+        sims,
+        path_dir=tmp_path,
+        local_gradient=False,
+        verbose=False,
+    )
+
+    grad_fd = np.zeros(3, dtype=float)
+    for idx, axis in enumerate("xyz"):
+        obj_plus = _eval_objective_components(
+            sim_data_map[f"{label}_fd_{axis}_plus"], monitor_components
+        )
+        obj_minus = _eval_objective_components(
+            sim_data_map[f"{label}_fd_{axis}_minus"], monitor_components
+        )
+        grad_fd[idx] = (obj_plus - obj_minus) / (2 * delta)
+
+    angle = angled_overlap_deg(grad_adjoint, grad_fd)
+    print(f"[{label}] grad_adjoint = {grad_adjoint}", file=sys.stderr)
+    print(f"[{label}] grad_fd      = {grad_fd}", file=sys.stderr)
+    print(f"[{label}] angle_deg    = {angle}", file=sys.stderr)
+
+    assert angle < 5.0

tests/test_components/autograd/test_adjoint_monitors.py

@@ -7,7 +7,7 @@
 
 import tidy3d as td
 
-SIM_FIELDS_KEYS = [("dummy", 0, "geometry")]
+SIM_FIELDS_KEYS = [("structures", 0, "geometry")]
 
 POLY_VERTS_2D: np.ndarray = np.array(
     [