Modeling

Emission Detectors

Configure Power Dissipation, Intensity, and Mode detectors

This guide explains how to enable the Power Dissipation, Intensity, and Mode emission detectors in Optics and what each one produces. Afterward, you can choose detectors for your analysis goal.

Prerequisite: complete Emitter Setup first.

Emission lane in the Optics page

Emission detectors are driven by in-layer emitters (EML), not external incidence. They are NOT affected by Incident Light, Incident Angle, P-Ratio, Cone Angle, or Incident Spectrum settings. Those parameters apply only to the Propagation lane detectors.

The Emission lane

The Emission lane provides three detectors:

Detector	Output
Power Dissipation	Emitter dipole power coupled into in-plane wavevectors (power dissipation spectrum). Results: Power Dissipation.
Intensity	Far-field emission intensity vs. wavelength (and optionally angle). Results: Intensity.
Mode	Guided and leaky optical modes supported by the emissive structure. Results: Mode.

Structure support

Material and single-layer limits

Layer role	Incoherent	Birefringent	Absorbing	Additional rule
Regular layer	✅	✅	✅	Incoherence and birefringence cannot be enabled together
Emissive layer (EML)	❌	✅	❌	With Transparent enabled, extinction coefficients are set to `0`; with it disabled, validation passes only when they are already `0`
Top Medium	—	❌	❌	—
Bottom Medium	—	❌	✅	—

“Birefringent” in this table means uniaxial birefringence with the optical axis normal to the film plane. Tilted or arbitrary optical axes and biaxial materials are not supported. Top Medium and Bottom Medium do not use the coherent/incoherent setting, so that column is marked “—”.

Detector support by structure

The table below assumes every layer already satisfies the material and single-layer limits above. “First structure layer” means the first finite-thickness film after Top Medium.

Structure scenario	Power Dissipation	Intensity	Mode
One EML and all structure layers coherent	✅	✅	✅ Conditional*
Multiple EMLs and all structure layers coherent	✅	✅	✅ Conditional*
The first structure layer is the only incoherent layer	✅	✅	✅ Conditional*
An incoherent layer is not the first structure layer	✅	✅	❌
More than one incoherent layer is present	✅	✅	❌
EMLs are separated by an incoherent layer	✅	✅	❌

* Mode conditions:

With no top incoherent layer: $n_{\mathrm{top}}<n_{o,\mathrm{EML}}$
When the first structure layer is the only incoherent layer: $n_{\mathrm{top}}<n_{\mathrm{inco}}<n_{o,\mathrm{EML}}$
When Bottom Medium is transparent: $n_{\mathrm{bottom}}<n_{o,\mathrm{EML}}$
When Bottom Medium is absorbing, calculation is allowed, but BOC is 0.
With multiple EMLs, every EML must satisfy the applicable conditions above.

Here, $n_{\mathrm{top}}$ is the Top Medium index, $n_{\mathrm{inco}}$ is the index of the incoherent first structure layer, $n_{\mathrm{bottom}}$ is the Bottom Medium index, and $n_{o,\mathrm{EML}}$ is the EML ordinary index.

Wavelength modes

Available wavelength modes per detector:

Detector	Single	Sweep	Weighted Average
Power Dissipation	Yes	Yes	No
Intensity	Yes	Yes	Yes
Mode	Yes	Yes	Yes

Power Dissipation has no Weighted Average mode. The option is not available for that detector. For spectrally weighted emission power information, use the Intensity detector in Weighted Average mode instead.

Mode behavior:

Single: Calculates at one specified wavelength; result is a one-dimensional distribution (in-plane vector or angle as the x-axis).
Sweep: Calculates at each wavelength from From to To in Step increments; result includes the full spectral dimension, with heatmap and line-chart display options.
Weighted Average (Intensity / Mode only): Collapses the wavelength dimension to one effective result. Intensity uses radiant-power spectral weights, while Mode uses photon-number spectral weights. Both are derived from the emitter's Spectrum Unit, making the mode useful for comparing full-spectrum intensity or outcoupling behavior across structures.

At a fixed wavelength, Mode depends on the structure, refractive indices, dipole position, orientation, and other optical conditions—not on the spectrum amplitude. Spectrum unit and lineshape enter Mode only when wavelengths are combined in Weighted Average.

The same physical spectrum expressed as Probability and Power should produce the same Weighted Average when converted with

E_\gamma=hc/\lambda

. Here,

E_\gamma

is the photon energy,

h

is the Planck constant,

c

is the speed of light in vacuum, and

\lambda

is wavelength.

Per-detector configuration

Power Dissipation

In addition to wavelength parameters, Power Dissipation requires an In-plane Vector Type to define the x-axis physical quantity:

Option	Label	Default range
`nEff`	Effective Index (nEff)	0 → 2.0, step 0.01
`In-plane k`	In-plane k	0 → 1, step 0.01
`In-plane u`	In-plane u	0 → 1, step 0.01

The default is nEff (effective refractive index).

Intensity

In addition to wavelength parameters, Intensity has an Angle Mode:

Option	Description
Single	Samples far-field intensity at one specified angle only.
Sweep	Samples across an angle range from `From` to `To` at `Step` intervals. Default: 0°–80°, step 5°.

Angle constraints: 0° ≤ angle ≤ 90°; Sweep mode requires angleTo > angleFrom.

Mode

In addition to wavelength parameters, Mode has a Tolerance field:

Default: 1e-4
Controls mode-search convergence precision; must be greater than 0.
Wavelengths with unconverged modes are marked with * in the results.

Intensity Color

Intensity Color is a derived feature of the Intensity detector that computes CIE chromaticity coordinates and visible emission color.

Enabling Visible Color requires all three conditions to be met simultaneously:

Intensity detector is enabled
Wavelength Mode is Sweep (not Single or Weighted Average)
The sweep covers 360–780 nm at step ≤ 5 nm

If Wavelength Mode changes away from Sweep, Visible Color is automatically disabled.

When Wavelength Mode is not Sweep, the Visible Color toggle is disabled and shows the tooltip:

Visible Color can only be enabled when Wavelength Mode is Sweep.

Intensity Color configuration tooltip

If the current configuration does not meet the requirements, a hint is shown alongside an auto-fix button: clicking it enables the Intensity detector and sets the wavelength sweep to 360–780 nm at step 1 nm in a single action.

Color calculation allows a step up to 5 nm, but use 1 nm for color comparison. When the actual result spacing is greater than 1 nm, the Intensity Color page shows a nonblocking coarse-sampling note. Narrow emission peaks with FWHM below about 10 nm are especially sensitive to grid placement.

Color output also requires selecting a chromaticity observer:

2° (default)
10°

CCT and Duv are available only with the 2° observer. The 10° observer uses the CIE 1964 chromaticity locus and omits those two metrics. See Intensity Color for per-angle metrics and baseline comparison.

Detector guards

At least one detector must remain enabled (Propagation and Emission lanes are counted independently). When all detectors are off, clicking Run produces no request and no error — the calculation is silently skipped.

When the structure has no emissive layer (EML):

An info banner is shown at the top of the Emission lane: "No emissive layer (EML) in the structure. Mark a layer as emissive on the Structure page to enable Emission detectors."
Emission detector cards are not disabled — users can still freely check or uncheck detectors. Cards are only locked while a calculation is in progress.

Configure sweep parameters: Parameter Sweep
View simulation results: Power Dissipation · Intensity · Intensity Color · Mode

Emitter Setup

Mark an emissive layer and configure its emitters

Swept Emission

Sweep emitter properties and read swept emission results