Pulsed Laser
Emits a mode-locked pulse train; its bandwidth follows the pulse duration while transform-limited, or is set by hand.
Open in the canvas →In the real world
A pulsed laser concentrates its output into short bursts separated by a fixed repetition period, rather than emitting steadily. Concentrating a given pulse energy into a shorter duration — in addition to spatial concentration at a focus — enables substantially higher intensities than continuous-wave operation can achieve; the most extreme intensities produced this way are employed in high-field physics, and more modest ones drive the nonlinear processes behind multiphoton microscopy and two-photon polymerization.
Pulse durations range from microseconds down to a few femtoseconds. The average power a power meter reads is the pulse energy divided by the repetition period; the peak power reached within a pulse is far larger, by roughly the ratio of the repetition period to the pulse duration.
Ultrafast lasers are inherently broadband: a sufficiently short pulse duration necessarily corresponds to a correspondingly broad frequency spectrum. A pulse whose spectral width is exactly the minimum its duration allows is called transform-limited — it carries no residual chirp, and it is the shortest pulse that spectrum could possibly support. The dimensionless product below depends only on the envelope shape.
Short pulses are produced by mode locking: a fixed phase relationship is enforced across many longitudinal cavity modes, so that they interfere constructively for a brief instant on each cavity round trip and destructively the rest of the time. The repetition rate that results is set by the cavity round-trip time, which is why typical mode-locked oscillators sit in the tens of MHz.
In OpticalSetup
The Pulsed Laser emits the same collimated ray or 25-ray sampled beam as the CW Laser, plus a pulse train: a repetition rate, a pulse duration, and an emission offset that shifts this source's pulses in time relative to any other. That timing is what drives the travelling packet overlay, the oscilloscope view on a photodetector, chopper and AOM/EOM gating, and the two-colour temporal overlap that CARS and SFG require.
Bandwidth follows the pulse: while Transform-limited is on, the spectral width is computed from the duration and the chosen envelope shape, so a shorter pulse automatically becomes a wider spectrum. Turning it off exposes the bandwidth directly for a chirped or spectrally shaped pulse; setting it to 0 nm models an idealized monochromatic pulse train. Peak power is reported back as a derived readout, never entered.
Show pulse dynamics is a drawing choice only — switching it off leaves the beam rendered as a steady CW line while every bit of the pulse physics above keeps running.
Dispersion and pulse stretching
Every pulsed detector reports accumulated group-delay dispersion (GDD) in fs². Catalogue-glass bodies add their traced distance through the selected Sellmeier material; zero-thickness lenses and objectives add the clearly marked estimates described on their own pages. For a transform-limited Gaussian input, the detector also reports the corresponding broadened duration, and the travelling packet length follows that duration locally: it grows through glass and contracts when a Pulse Compressor cancels the accumulated GDD. GDD remains the primary number because it is additive and meaningful even when a 150 fs pulse changes too little to notice.
There is no modeled gain medium, cavity, or mode-locking mechanism — repetition rate, duration, and shape are configured directly. The duration estimate uses second-order GDD only and is shown only for a transform-limited Gaussian input; pre-existing chirp, third- and higher-order dispersion, self-phase modulation, and material absorption are not inferred. Divergence and M² are not modeled.