Every optical material has an index that varies with wavelength, so different colors bend and travel differently. Spatially it causes prism splitting and chromatic aberration in lenses; in time it spreads pulses, described by group delay, GVD and higher orders. In fibers it combines material and waveguide contributions and is quoted as D in ps per nm per km, about 17 at 1550 nm in standard singlemode fiber.
Chromatic dispersion in that singlet throws the 400 nm focus half a millimeter short of the 800, swap in an achromat.
Also heard as
- dispersion
- CD
Do not mix it up with
- GVD: GVD is one specific measure of chromatic dispersion that governs how much a pulse stretches.
Related terms
GVD
Group Velocity Dispersion: how strongly a material's group velocity changes with wavelength, which stretches short pulses.
Chirp
A change in instantaneous frequency across a pulse, so its colors arrive spread out in time.
Walk-off
The drifting apart of interacting beams in a crystal, either sideways from birefringence or in time from velocity mismatch.
Phase matching
Keeping interacting waves in a nonlinear crystal in step so the generated light builds up instead of canceling.