Depth-Resolved Quantities
Depth-resolved quantities describe how energy flux, absorption, and fields are distributed through the thickness of the stack. They are used to locate standing waves, local absorption peaks, and field-enhancement regions.
Scope of this chapter
| Quantity | Focus | Result page |
|---|---|---|
Poynting Vector | Net energy-flow distribution through depth | Depth-Distribution Results |
Absorption Density | Location of local dissipation | Depth-Distribution Results |
Electric Field | Magnitude, phase, and component variation through depth | Depth-Distribution Results |
| Data structure | Organization of wavelength-depth matrices | Depth-Distribution Results |
Shared data structure of depth outputs
The app stores depth outputs as matrices over a globally expanded depth axis.
| Data item | Current structure | Physical meaning |
|---|---|---|
depth_point_list | 1D array | Global depth coordinates in nm |
layer_info_list | Per-layer start and end depth metadata | Used to mark layer boundaries in plots |
| Depth matrices | Typically [wavelength_index][depth_index] | Distribution versus depth at each wavelength |
| Complex electric-field values | Ex / Ey / Ez stored as [real, imag] | Used to derive magnitude and phase displays |
When reading these plots or tables, separate the two axes:
- the wavelength dimension;
- the depth dimension through the stack.
Heatmaps and tables are different views of the same matrix data. Sweep views add the parameter-combination dimension on top of that matrix.
Poynting Vector: energy flow through the stack
The Poynting Vector page shows the normalized normal (z-direction) component of the energy flux.
| Reading point | Practical use |
|---|---|
| Higher values indicate stronger net forward energy flow at that depth | Determine the main energy-transport path |
| A continuous decay with depth usually indicates absorption | Quickly identify the loss location |
| Strong variation near interfaces usually indicates interference or standing-wave redistribution | Judge whether interface reflections are dominating the field pattern |
Use this quantity to check:
- whether optical power reaches the target region;
- whether power is mainly reflected or dissipated near the front of the stack.
Absorption Density: local dissipation
Absorption Density measures local energy dissipation per unit volume. For total absorption by layer, compare it with Layer Absorption in Basic Optical Results.
| Reading point | Practical use |
|---|---|
| Peak regions correspond to the strongest local absorption | Locate the active absorber or parasitic loss layer |
| If strong absorption appears in a layer that should be nearly transparent, the material model is likely wrong | Check index files and stack ordering |
Compared together with Poynting Vector, it separates “energy passing through” from “energy being consumed” | Distinguish transport-limited behavior from absorption-limited behavior |
For absorbing devices, this directly shows whether the absorption occurs in the intended layer.
Electric Field: magnitude, phase, and components
The Electric Field page includes component, magnitude, and phase information.
| View | Current data | Main information |
|---|---|---|
| Components | Ex, Ey, Ez | Dominant field direction |
| Magnitude | Derived Magnitude view | Field-enhancement locations |
| Phase | Ex_phase, Ey_phase, Ez_phase | Nodes, phase jumps, and standing-wave structure |
The three views expose different information:
Magnitude: location of field enhancement;Component: dominant field component;- Phase: nodes, phase flips, and standing-wave structure.
Resolution and data-volume limits
The most common failure mode in depth-resolved analysis is excessive data volume. The frontend applies explicit thresholds to keep rendering stable.
| Item | Current threshold | Purpose |
|---|---|---|
| Maximum table rows | 500,000 | Above this, table rendering is blocked |
| Maximum 2D chart points | 500,000 | Above this, chart rendering is blocked or downgraded |
Maximum scatter3D points | 80,000 | Stricter 3D limit because GPU and memory load are higher |
Maximum bar3D points | 50,000 | 3D bar geometry is more expensive than scatter |
| Chart optimization threshold | 100,000 | Above this, smoothing, animations, and dense point markers are reduced |
| Single-request TMM solve count | 50,000 | Backend safety limit to prevent timeout or memory exhaustion |
As Depth Resolution becomes smaller, the number of depth points increases. As total thickness increases, it also increases. Therefore:
- a finer resolution is denser, not automatically better;
- a thick substrate kept coherent can create very large datasets;
- in sweep mode, total data size also scales with the number of parameter combinations.
Field-related detectors require a fully coherent stack
Field-related detectors depend on coherent field solutions. Refractive Index only expands the structure itself and does not require a fully coherent stack.
| Detector | Requires a fully coherent stack | Reason |
|---|---|---|
Poynting Vector | Yes | It depends on the coherent field solution |
Absorption Density | Yes | It depends on coherent fields and local dissipation |
Electric Field | Yes | It directly uses field components and phase |
Refractive Index | No | It is only a depth expansion of the structure, not a coherent field result |
Use Refractive Index when you only need to verify the expanded structure. Use field and energy-flow detectors only with a fully coherent stack.
Analysis order
Use the depth outputs in this order:
Poynting Vector: confirm whether energy reaches the region of interest.Absorption Density: locate where that energy is dissipated.Electric Field: explain enhancement, nodes, and component-dependent behavior.