Curved-element meshing and Palace 3D photonics example

.gitignore

@@ -20,6 +20,7 @@ uv.lock
 *.sage.py
 *.so
 *.spec
+*.lyp
 .Python
 .cache
 .coverage

nbs/_palace_dc.py

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+# ---
+# jupyter:
+#   jupytext:
+#     text_representation:
+#       extension: .py
+#       format_name: percent
+#       format_version: '1.3'
+#       jupytext_version: 1.19.2
+#   kernelspec:
+#     display_name: .venv
+#     language: python
+#     name: python3
+# ---
+
+# %% [markdown]
+# # Palace Directional Coupler Simulation - Wave Ports
+#
+# This notebook mirrors the geometry in [meep_dc.ipynb](meep_dc.ipynb), but configures a Palace driven simulation with waveport boundary conditions.
+#
+# MEEP-specific features (for example FDTD PML/animation details) are omitted.
+
+# %% [markdown]
+# ### Load the same directional coupler geometry
+
+# %%
+from pathlib import Path
+
+import gdsfactory.component as gfc
+from ubcpdk import PDK, cells
+
+# Use a workspace-local temp path for layer preview artifacts.
+gds_tmp = Path.cwd() / ".gdsfactory_tmp"
+gds_tmp.mkdir(parents=True, exist_ok=True)
+gfc.GDSDIR_TEMP = gds_tmp
+
+PDK.activate()
+
+c = cells.coupler()
+
+cc = c.copy()
+cc.draw_ports()
+cc
+
+# %% [markdown]
+# ### Configure Palace driven simulation with waveports
+
+# %%
+from gsim.palace import DrivenSim
+
+sim = DrivenSim()
+sim.set_output_dir("./palace-sim-dc-waveport")
+sim.set_geometry(c)
+
+sim.set_stack(
+    substrate_thickness=2.0,
+    add_oxide_dielectric=False,
+    add_passivation_dielectric=False,
+)
+
+# Use direct sparse solve backend.
+sim.set_numerical(
+    solver_type="MUMPS",
+    max_iterations=1,
+    tolerance=1e-8,
+)
+
+for i, port in enumerate(c.ports):
+    sim.add_wave_port(
+        str(port.name),
+        layer="core",
+        z_margin=1.5,
+        lateral_margin=1.5,
+        max_size=False,
+        mode=1,
+        excited=(i == 0),
+    )
+
+# Around 1.55 um (~193.5 THz).
+sim.set_driven(fmin=190e12, fmax=200e12, num_points=21)
+
+print(sim.validate_config())
+
+# %%
+import gdsfactory as gf
+
+active = gf.get_active_pdk()
+print("Active PDK:", active.name)
+
+stack = sim._resolve_stack()
+print("Stack layers:")
+for name, layer in stack.layers.items():
+    print(
+        f"  - {name}: type={layer.layer_type}, material={layer.material}, "
+        f"gds={tuple(layer.gds_layer)}, z=({layer.zmin}, {layer.zmax})"
+    )
+
+print("\nMaterial properties (selected):")
+for key in ("si", "sio2", "SiO2", "air"):
+    if key in stack.materials:
+        print(f"  - {key}: {stack.materials[key]}")
+
+print("\nDielectric regions:")
+for d in stack.dielectrics:
+    print(f"  - {d}")
+
+# %% [markdown]
+# ### Generate mesh
+
+# %%
+sim.set_airbox(
+    margin_x=0.0,
+    margin_y=1.5,
+    z_above=0.5,
+    z_below=0.5,
+)
+
+# fmax=220 THz -> lambda0~1.36 um. In Si (n~3.45), lambda~0.395 um,
+# so for >=5 points per wavelength use mesh size <=0.079 um.
+sim.mesh(
+    preset="fine",
+    refined_mesh_size=0.05,
+    max_mesh_size=0.25,
+    fmax=220e12,
+    curve_fit_mode="bspline",
+    curve_fit_layers=["core", "core2"],
+    curve_fit_tolerance_um=0.01,
+    curve_fit_min_points=8,
+    high_order_elements=True,
+    high_order_order=2,
+    high_order_optimize=True,
+)
+
+# %%
+sim.plot_mesh(
+    style="solid",
+    transparent_groups=["air__None"],
+    interactive=True,
+)
+
+# %% [markdown]
+# ### Run simulation
+
+# %%
+for p in sim._last_mesh_result.port_info:
+    print(
+        f"{p['type']} P{p['portnumber']}: "
+        f"z=({p['zmin']:.3f}, {p['zmax']:.3f}), "
+        f"x=({p['xmin']:.3f}, {p['xmax']:.3f}), "
+        f"y=({p['ymin']:.3f}, {p['ymax']:.3f})"
+    )
+
+# %%
+import json
+from pathlib import Path
+
+# For photonic sims, bypass conductor-oriented mesh validation.
+config_path = sim.write_config(photonic=True)
+cfg = json.loads(Path(config_path).read_text())
+print("Solver.Linear:", cfg["Solver"]["Linear"])
+
+results = sim.run_local(num_processes=16, verbose=True)
+
+# %% [markdown]
+# ### Plot S-parameters
+
+# %%
+results.plot_interactive()
+
+# %%
+results.plot_interactive(phase=True)