Interpreting Results

Intensity

Angular and spectral emission intensity, global peaks, envelope FWHM, and normalized views

This guide introduces the spectrum, angular-distribution, global-peak, envelope-FWHM, and normalized views in Intensity. These views show the far-field intensity of a light-emitting device and reduce each complete spectrum to scalar results that are convenient for scan comparisons.

Spectral weight and source strength

The far-field contribution of one emitter can be summarized as

I_i(\theta,\lambda)\propto M_iC_i\Lambda_{P,i}(\lambda)R_i(\theta,\lambda)

Here, $I_i(\theta,\lambda)$ is the intensity contribution of emitter $i$ at output angle $\theta$ and wavelength $\lambda$ . $M_i$ is its Multiplication Factor, $C_i$ is its Conversion Efficiency, $\Lambda_{P,i}(\lambda)$ is its radiant-power spectral weight, and $R_i(\theta,\lambda)$ is the far-field response determined by the structure, dipole position, and orientation.

With Spectrum Unit set to Probability, the input photon-number spectrum is converted to power using the photon-energy factor $hc/\lambda$ . With Power, the input values are used directly as $\Lambda_P$ . Here, $h$ is the Planck constant and $c$ is the speed of light in vacuum. For one emitter, $M_i$ and $C_i$ scale raw intensity linearly but do not change a normalized spectrum or normalized angular distribution. With several emitters, different weights can change the combined spectrum, angular distribution, and color.

Example Setup

The example is a green top-emitting OLED: Air / Ag / BPhen / Alq₃ EML / NPB / Al / BK7. Ag and Al use measured dispersion from the refractive-index database. BPhen and NPB use quartz-substrate variants from the Aulika OLED material database. No matching Alq₃ entry is available, so the EML retains a constant refractive index and uses a generated emission spectrum that covers the complete calculation band.

Top-emitting OLED structure with file-based refractive-index materials for Ag BPhen NPB and Al and an emissive Alq3 layer — Figure 1 | Top-emitting OLED structure used for the spectrum metrics

Intensity detector configured for a 400 to 700 nm wavelength sweep and a 0 to 60 degree angle sweep — Figure 2 | Intensity wavelength and angle sampling

Item	Example value
Top / bottom medium	Air / BK7 Glass
Layer stack	Ag 15 nm / BPhen 30 nm / Alq₃ 40 nm / NPB 40 nm / Al 100 nm
Database materials	Ag (Johnson and Christy 1972), BPhen (Qz, 82 nm), NPB (Qz, 287 nm), Al (McPeak et al. 2015)
Emitter	Alq₃ with a generated broadband spectrum peaking near 530 nm
Intensity wavelength	400–700 nm, 10 nm step
Output angle	0–60°, 20° step

The BPhen and NPB entries match the material chemistry and cover the required wavelength band, but their measurement substrates and film thicknesses do not match the adjacent layers and thicknesses in this device. This setup demonstrates result reading. For quantitative design, select data that match the process or upload measured

n,k

for the actual films.

Spectrum

When Wavelength Mode is set to Sweep, the Intensity page shows far-field emission intensity (a.u.) vs. wavelength (nm) for each polarization channel.

Polarization: switch between TE / TM / Total using the polarization SelectButton. All three curves can be shown simultaneously, or a single curve selected through the legend.

Chart type: when only the wavelength dimension is present (Angle Mode = Single or Weighted Average), the default is a line chart. When an angle sweep is also active (Angle Mode = Sweep), the chart can be toggled between line and heatmap, and the x-axis can be switched between Wavelength and Angle.

Single-value mode (angle = Single and wavelength = Single or Weighted Average): the chart area is hidden and the page switches to table-only mode.

Emission intensity spectrum plotted against wavelength — Figure 3 | The raw Intensity spectrum retains every wavelength sample

Spectrum Peaks and Envelope FWHM

When Intensity uses a Sweep with at least two wavelength samples, the Results area provides three derived views. They read only the raw Intensity spectrum; normalized spectra, single-wavelength results, and Weighted Average results are not used as sources.

For each spectrum identified by “scan combination × output angle × polarization,” define

I_\text{peak}=\max_{\lambda} I(\lambda)

I_{1/2}=0.5I_\text{peak}

\Delta\lambda_\text{env}=\lambda_R-\lambda_L

Here, $I_\text{peak}$ is the Global Peak Intensity, Peak Wavelength is the wavelength of the unique highest raw sample, $I_{1/2}$ is the half-maximum level, $\lambda_L$ and $\lambda_R$ are the outermost half-maximum crossings, and $\Delta\lambda_\text{env}$ is Envelope FWHM in nm.

Metric	Definition
Global Peak Intensity	The largest sampled value in the complete raw spectrum
Global Peak Wavelength	The wavelength of the unique global-maximum sample; there is no peak-top fit and no local-peak tracking
Envelope FWHM	The outermost wavelength span occupied by all regions at or above half maximum

Half maximum is taken directly from the current y-values. There is no power/amplitude conversion, baseline subtraction, or smoothing. Crossings are linearly interpolated between neighboring samples, including on nonuniform wavelength grids. Total, TE, and TM are evaluated independently.

Data Status Interpretation

A data status indicates whether a metric can be determined uniquely and completely from the spectrum inside the current sampling range. It is not the success or failure state of a Run: a calculation can finish normally while Peak Wavelength remains nonunique or FWHM remains unresolved because the wavelength range clips it.

Data statuses appear in two places: Status summary in the chart sidebar counts each status, while the DataTable status column classifies every spectrum. The green Resolved 12 in Figure 4 means that all 12 spectra from four angles and three polarizations have complete FWHM values.

Envelope FWHM line chart versus angle with the status summary showing twelve resolved results — Figure 4 | Status summary on the right counts all angles and polarizations; all 12 spectra in this example are resolved

In a DataTable, first check whether the metric cell contains a value, then read the status in the same row. A blank means that the current spectrum cannot determine the metric completely; it does not mean zero. “Multiple half-max regions” retains an FWHM value, but that value is the outer span of the complete multipeak envelope.

The six panels in Figure 5 correspond to the six table rows from left to right and top to bottom.

Blue curve: the raw intensity spectrum.
Blue dots: samples at the global maximum. Multiple blue dots leave Peak Wavelength blank.
Orange dashed line: half of the global peak value.
Bright-green dots: valid crossings of the spectrum and the half-maximum line. The two outermost crossings determine Envelope FWHM.
Red marks: a sampling boundary or data gap prevents complete crossings, so FWHM is blank.

Six spectrum panels illustrating resolved ambiguous peak multiple half-max regions edge clipping no signal and a data gap — Figure 5 | Typical spectrum conditions for the six data statuses; the orange dashed line is half maximum and green dots are half-maximum crossings

UI status	Value result	Corresponding spectrum and action
Resolved	The corresponding metric is available	One highest point and a half-max region closed inside the wavelength range; compare directly
Ambiguous peak	Peak Intensity remains; Peak Wavelength is blank; FWHM is evaluated independently	Two or more samples equal the global maximum; inspect a plateau or equal peaks
Multiple half-max regions	Envelope FWHM and the region count remain available	A valley falls below half maximum; interpret the value as the outer span of the complete multipeak envelope
Edge clipped	FWHM is blank; Peak is evaluated independently	A wavelength boundary remains above half maximum; extend the wavelength range
No signal	All three metrics are blank	The spectrum is empty or its maximum is not positive; check source strength, the Intensity detector, and the structure
Data gap	All three metrics are blank	At least one wavelength sample is missing; repair the data and run again

Figure 6 is the real DataTable counterpart of “Edge clipped” in the lower-left panel of Figure 5. The example narrows the wavelength range to 520–540 nm, so the curve remains above half maximum at the boundary. The FWHM cell is therefore blank, the status is edgeClipped, and the half-max region count remains 1.

Envelope FWHM table with blank values edgeClipped status and one half-maximum region for Total TE and TM — Figure 6 | Edge clipping in a real DataTable; FWHM is blank while the half-max region count remains available

Results and Actions for Special Statuses

Boundary sample exactly equal to half maximum: the sample is a valid crossing and FWHM is returned normally.
Multiple half-max regions together with edge clipping: FWHM is blank and the status is “Edge clipped,” while the region count remains available. Extend the wavelength range and run again.
Peak Wavelength marked “Ambiguous peak”: only Peak Wavelength is blank. Peak Intensity remains available and FWHM is evaluated independently.

Multipeak Spectrum Rules
A multipeak spectrum still produces one set of global metrics: at most one Global Peak Intensity, one Global Peak Wavelength, and one Envelope FWHM for each spectrum and polarization.

If several peaks remain connected above half maximum, Envelope FWHM is the distance between the two crossings of that region.
If a valley falls below half maximum and creates several regions, Envelope FWHM is the distance from the leftmost to the rightmost crossing and is marked “Multiple half-max regions.”
If several samples equal the global maximum, Peak Intensity remains, Peak Wavelength is blank, and FWHM is evaluated independently.
If the unique highest sample is at a wavelength boundary, its sampled-domain Peak Wavelength remains valid.

For white-light or multi-emitter spectra, Envelope FWHM describes the span of the complete emission envelope, not the local linewidth of each R/G/B contribution. Local peaks, per-peak widths, peak tracking, and multipeak fitting require the raw spectrum.

Charts across scans

The real result below uses Angle Sweep, so angle is the only varying axis. The three polarizations are displayed directly as three line series and a legend; there is no duplicate polarization switch in the right sidebar.

Line chart of Total TE and TM global peak intensity versus output angle — Figure 7 | Each complete spectrum produces one Global Peak Intensity per angle and polarization

Line chart of Total TE and TM global peak wavelength versus output angle — Figure 8 | Global Peak Wavelength can jump when the dominant spectral lobe changes; the line only connects the global result of each scan state

Angular distribution

When Angle Mode is set to Sweep, the chart shows far-field emission intensity (a.u.) vs. angle (deg) for each polarization channel. This view is equivalent to the Angular Spectrum sub-view (the sidebar entry Angular Spectrum is a sub-view within Intensity, not a standalone page).

Polar view: in line-chart mode, enable the Polar Toggle to switch to a polar plot. The polar chart uses 360° mirror symmetry, startAngle = 90, and normalizes the radial axis to the series maximum.

Values: raw far-field intensity, without normalization. To compare shape across angles with normalization applied, use Normalized Angular Distribution.

Normalized angular-distribution result — Figure 9 | Normalized angular distribution is useful for comparing emission-cone shape

Normalized views

Normalized Spectrum

Normalization definition: each (angle, polarization) series is scaled so its peak = 1 across wavelengths. TE / TM / Total are normalized independently.

The x-axis is locked to Wavelength (nm); the y-axis is Normalized Intensity. There is no x-axis selector and no chart-type toggle—line chart only.

This view uses the same underlying data as Angular Spectrum, but normalization removes the absolute intensity difference between angles, making it suitable for directly comparing emission spectral shapes across different emission angles.

Normalized Angular Distribution

Normalization definition: each (wavelength, polarization) series is scaled so its peak = 1 across angles. TE / TM / Total are normalized independently.

The x-axis is locked to Angle (deg); the y-axis is Normalized Intensity. Line chart is the default; in line mode the Polar Toggle is available.

This view uses the same underlying data as Angular Spectrum, but normalization removes the absolute intensity difference between wavelengths, making it suitable for comparing the shape of emission lobes across different wavelengths.

Normalized views retain shape information only. They do not reflect absolute intensity magnitude and are not the source for the three global metrics. To inspect the intensity relationship between channels, use the raw curves in Intensity or Angular Spectrum.

Controls

Common export and copy controls (Export CSV, Export Image, Copy Image) are described in Basic Optical Results. Controls specific to this page and its derived views are:

Control	Function
Polarization SelectButton	Switch TE / TM / Total in two- or three-dimensional derived charts; one-dimensional derived charts show all three in the legend
X-axis selector (Intensity 2D mode)	Switch the x-axis between Angle and Wavelength
Chart type	Switch a two-dimensional result between Line and Heatmap
Polar Toggle	Switch an angular distribution to a polar plot
Status summary	Count valid, warning, and missing points for the current derived metric
Legend select / invert	Click a legend item to isolate one series; click again to restore all

After reviewing intensity and spectral width, go to Intensity Color for CIE chromaticity and visible-color output. If Peak Wavelength jumps or FWHM reports a warning, return to the raw spectrum on this page first.

Power Dissipation

Read dissipated power versus in-plane wave vector

Intensity Color

CIE chromaticity of the emission spectrum