38 -- A four-grating compressor, grating by grating¶

A compressor on the command line. Each grating and slant path is its own element, so the tracker follows the beam's spatial chirp through the line (Components).

The overview figure of this example's run (python make_figures.py redraws it; the file is hero.png).

cd docs/examples/LaserSystems/four-grating-compressor
ultrafast run compressor.ufs run.json -o results
python report.py

g1   spatial chirp     0.000 mm per 100 nm   GDD          0 fs2
a    spatial chirp    28.279 mm per 100 nm   GDD     773731 fs2
g2   spatial chirp    23.561 mm per 100 nm   GDD    -773731 fs2
mid  spatial chirp    23.561 mm per 100 nm   GDD    -773731 fs2
g3   spatial chirp    28.279 mm per 100 nm   GDD   -2321192 fs2
b    spatial chirp     0.000 mm per 100 nm   GDD   -1547462 fs2
g4   spatial chirp     0.000 mm per 100 nm   GDD   -1547462 fs2
Treacy, two pairs  -1547449 fs2

The second pair is the mirror image of the first, so the spatial chirp opens and closes exactly, and the total GDD is that of two single passes (Treacy, 0.001 %). The GDD changes sign inside a pair because a slant path adds its own dispersion before the second grating removes more.