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Crystal transition (supplemental)

Supplemental Tidy3D study of the crystal transition region.

No top-level README -- this is the most complete of four dated Tidy3D runs under results/; the other three (20260507_120157, 20260507_120406, 20260507_122710) cover earlier parameter choices.

Generated: 2026-05-07T12:29:37

Purpose

Estimate power coupled from the fundamental TE-like mode of a crystal-covered Si3N4 waveguide into the fundamental TE-like mode of the corresponding bare PVA-clad Si3N4 waveguide across an abrupt transition.

Geometry and Materials

  • Coordinates: x is propagation, y is lateral, z is vertical.
  • The Si3N4 waveguide center is at z=0.
  • Wavelength sweep: 760.0-800.0 nm with center 780.0 nm.
  • Si3N4 waveguide: 450.0 nm wide, 300.0 nm thick, n=2.
  • SiO2 substrate: thickness 1.2 um, n=1.45.
  • PVA cladding: n=1.5.
  • Crystal: 200.0 nm thick, full lateral simulation width, n=1.8.
  • Simulation size: 10 um x 4 um x 3 um.
  • Source x: -3 um; output mode monitor x: 3 um.

Geometry Plots

geometry_z0_top_view

geometry_y0_cross_section

geometry_x_input_cross_section

geometry_x_output_cross_section

Mode Profiles

The mode profiles are local eigenmode solves at the source plane in the crystal-covered region and at the output monitor plane in the bare region.

injected_mode_profile

measured_bare_mode_profile

FDTD Results

transmission_vs_wavelength

field_intensity_z0

Downloaded simulation data: simulation_data.hdf5

Reproducibility

The script builds one 3D FDTD simulation with an abrupt crystal step at x=0. All material models are nondispersive constants unless CLI overrides are supplied.

Downloads

FDTD simulation study only -- no GDS/STL deliverable files exist in this tree.

Source: nanophotonic_devices/emitter_coupling/crystal_transition_supplemental_v1/