Interactive THz education

Spatiotemporal THz Electric-Field Explorer

Explore how a mechanical delay scan becomes a three-dimensional terahertz electric-field dataset, how the Fourier transform produces frequency-resolved images, and how scan length, time sampling, frequency resolution, pulse width, bandwidth, and Nyquist frequency are connected.

Stage scan span
2.000 mm
(N − 1) × stage step
Time step
66.713 fs
Sampling interval between images
Time window
13.343 ps
First-to-last recorded delay
Frequency resolution
0.07458 THz
Spacing between FFT bins
Nyquist frequency
7.495 THz
Maximum representable frequency
Frequency frames
101
Non-negative rFFT bins including DC
Pulse width
1.067 ps
Electric-field envelope FWHM
Usable bandwidth
—
Above the selected spectral threshold

Time-domain THz pulse

Signed electric field and its positive envelope.

E(t)

THz spectrum

Numerical Fourier-transform amplitude of the simulated pulse.

|E(f)|

Time-domain spatial frame

Instantaneous signed electric-field component and local vectors.

t = 0 ps

Frequency-domain spatial frame

Spatial spectral amplitude at the selected FFT frequency bin.

f = 0 THz

Spatiotemporal x–t field map

A horizontal line through the beam is followed through the complete delay scan.

space × time

1. Time images

The detector records one two-dimensional electric-field image at every delay position. Stacking the images produces E(x, y, t).

2. Fourier transform

An FFT is applied along the time axis independently at every spatial pixel. Each FFT bin becomes one frequency-resolved image.

3. Important distinction

The delay-stage time step is the sampling interval, not the full instrument temporal resolution. Detector response and gate-pulse duration can further limit the experiment.