Anthracene dual-angle waveguide

Straight collection guide + a 45-degree tilted pump guide meeting a cleaved SiO2 chip surface.

FDTD study of a DBT-like, x-polarized emitter in a 200 nm anthracene crystal on silver. Two Si3N4 waveguides in a cleaved SiO2 chip touch the top crystal surface:

• a straight collection guide normal to the crystal;
• a pump guide in the y-z plane, tilted 45 degrees from the z normal.

The tilted-guide facet is the intersection of the oblique core with the horizontal cleave plane, so its y extent is larger by 1/cos(45 degrees).

The sweep varies the y coordinate of the tilted-guide facet center: 2.0, 5.0, 8.0 um. These near, nominal, and far points keep the complete dipole/cross-talk study inside the authorized 5 FlexCredit cap.

Metrics

• Dipole beta factor into the straight fundamental mode.
• Dipole beta factor into the angled guided port (aperture flux, checked at two planes).
• Straight-to-angled power transfer. Reciprocity makes this equal to the requested angled-to-straight cross-talk.
• Relative angled-pump excitation strength from dipole-to-angled coupling, by Lorentz reciprocity.
• Estimated and actual billed FlexCredit cost.

Commands

cd nanophotonic_structures/anthracene_dual_angle_waveguide_v1
python study.py --dry-run
python study.py --estimate
python study.py --run --max-flexcredits 5
python study.py --report

--run estimates every missing job before starting any of them and refuses to submit the batch if the estimated total exceeds the supplied cap.

Results

Silver / anthracene dual-angle waveguide: two-polarization study

Method

For every offset and dipole orientation, two production simulations are used:

1. A point dipole (Ex or Ey) measures emitted power in the matching straight-guide mode and in the angled guided port.
2. A unit-power matching straight-guide mode is injected toward the crystal with no dipole source. Power reaching the angled port is the straight-to-angled cross-talk. Lorentz reciprocity makes it equal to angled-to-straight cross-talk.

The local mode solve identifies straight mode 0 as Ex-like and mode 1 as Ey-like. The angled guide is evaluated by two y-normal flux apertures because Tidy3D does not provide oblique mode-monitor planes.

Geometry

Results

Offset (um)	Dipole / mode	n_eff	beta straight	beta angled	cross-talk	cross-talk plane mismatch
2.0	Ex	1.6806	43.67%	1.119%	-20.37 dB	30.32%
2.0	Ey	1.6574	43.2%	0.3631%	-25.10 dB	25.49%
5.0	Ex	1.6806	43.64%	0.3391%	-25.91 dB	10.80%
5.0	Ey	1.6574	43.2%	0.07221%	-32.34 dB	9.54%
8.0	Ex	1.6806	43.65%	0.1593%	-29.37 dB	3.25%
8.0	Ey	1.6574	43.2%	0.02081%	-37.86 dB	25.94%

At the requested 5 um offset:

• Ex is the stronger straight-collection orientation.
• Ex is the stronger angled-guide emitter-coupling orientation.
• Ex cross-talk is -25.91 dB; Ey-family cross-talk is -32.34 dB.

Ex field intuition at 5 um

Ey field intuition at 5 um

field_reverse_xy.png.

Cost

• Initial mode-index screening: 0.4681 FC.
• Corrected Ex production runs: 0.4149 FC.
• Ey extension runs: 0.4987 FC.
• Total billed study cost: 1.3817 FC of the authorized 5 FC.

Limitations

• Straight-guide powers use exact modal decomposition.
• Angled-guide powers use aperture flux rather than an oblique modal decomposition; the two-plane mismatch is reported for every cross-talk result.
• The in-plane Ey/Ez polarization family remains separate from Ex by x-mirror symmetry, but the angled-port aperture sums any guided power within that family.
• Results are monochromatic at 780 nm and assume an ideal planar cleave, isotropic anthracene, and the stated dipole axes.

Downloads

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

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Source: nanophotonic_devices/emitter_coupling/anthracene_dual_angle_waveguide_v1/