Historical derivation — preserved in full

Source: design23_autonomous_optimizer_v1.0.0/design23_autonomous_optimizer/multilayer_nanobeam_phase17/README.md
Snapshot: design23-v1.0.0. The body below is unabridged.

Multilayer nanobeam — Phase 17

This phase reconstructs the complete QNM Green residue at a point inside the SiN core. The point/hole maps use the same complex-beta feed subtraction and exact real-space feed restoration as the accepted cavity operator. The residue is independent of eigenvector normalization and converts directly to an Ey-projected complex/effective mode volume.

The first benchmark point is (x,y,z)=(0,0,0). Observation inside the anthracene film requires an additional cross-layer Weyl transmission map and is intentionally the next extension rather than an effective-index shortcut.