Sweeps

A sweep simulates your design many times while one thing changes, and plots the power at every output. Use it for spectra (a ring’s resonance, a filter’s passband, a WDM link’s channels) and for tuning (how a phase shifter steers an interferometer, where a coupler reaches critical coupling).

Opening a sweep

• Inspector → Simulation → Sweep…: sweeps the selected part, or the first laser.
• Right-click a laser, phase shifter, attenuator, beam splitter or a waveguide block → Sweep…
• Analysis → Sweep… in the menu bar.

Selecting a laser sets up a wavelength sweep around its wavelength; selecting anything else sets up a parameter sweep over its first parameter.

Wavelength sweeps

Pick the laser to tune and the range in nm. The laser steps through the range; everything else stays as it is. This is how a tunable laser measures a device’s spectrum.

Parameter sweeps

Pick a part (Use selection) and one of its parameters, and the range:

Part	Parameters
Laser	power (mW), phase, wavelength
Beam splitter	reflectivity
Phase shifter	phase
Attenuator	transmission
Directional coupler	coupling
Phase shifter / attenuator blocks	phase / loss (dB)
Delay line	length, n_eff
MZI switch	θ, φ
Ring, add–drop ring	coupling, length, n_eff, loss (dB/cm)

Reading the plot

Every detector and output port is a curve, named by its label or its position. Tick Box outputs to also plot the light leaving every block and component (Add–drop ring 24,4 out2); they’re shown anyway when a design has no detectors. Click a name in the legend to hide or show it. The scale menu plots Power (mW), Power (dBm), or Relative to input (dB): each output over the input power, which is the tuned laser’s for a wavelength sweep and all lasers’ for a parameter sweep. That’s the transmission spectrum engineers quote. Scroll to zoom and drag to pan the plot; double-click resets it.

Readouts

Under the plot, a table gives for every curve shown:

Readout	What it is
Peak	highest power, and the swept value where it occurs
Minimum	lowest power, and where
Insertion loss	input over peak power, in dB: what the best path loses
Extinction	peak over minimum, in dB: how deep the switching or notch is

In the add–drop ring example, the drop port’s insertion loss is about 0 dB at resonance, and the through port’s extinction is over 20 dB.

Each point is a full simulation: light and electronics settle together, and components are simulated through. Coarse sweeps (tens of points) are instant; thousands of points on a big design take a few seconds.

Exporting

Copy CSV puts the data on the clipboard, ready to paste into a spreadsheet. Save CSV… writes a file (in the browser, it downloads). The first column is the swept value; then one power column (mW) per output.

A link can open a sweep directly: ?example=4-channel-wdm-optical-link&sweep opens the example and runs a sweep of its first laser.