I'm having fun learning about the physics of optical networks at a new job. It's fun connecting elementary physics learned so many years ago with how they're leveraged today in practical application.
My question is about the concept of
chromatic dispersion. I've read chromatic dispersion defined thus:
[T]he differential delay - or time spreading - in picoseconds of a wavelength generated by a laser that has a spectral width of 1 nanomater per kilometer of optical fiber.
In other words, different wavelengths of light at different speeds down optical fiber. Elsewhere:
Chromatic dispersion is commonplace, as it is actually what causes rainbows - sunlight is dispersed by droplets of water in the air.
I'm having trouble reconciling the description of chromatic dispersion as a displacement in time of wavelengths traveling through a medium versus the observed reality of the different colors/wavelengths of rainbows projected through a prism as being displaced in space. I.e. the time-related description of chromatic dispersion makes me think that the output through a prism should be a time-shifted cycle of colors from blue to red.
Can someone please help reconcile the time-related definition of chromatic dispersion with observed reality of prisms' output being dispersed in space, not time?