Laser frequency comb Fiber
What happens if you send the light of laser frequency comb (LFC) through a 100m long multi-mode (NA=0.23, core = 200µm) fiber? What looks like a glowing tornado viewed from the top is actually the light leaving the rear port of the fiber imaged onto a sheet of paper. The photo was captured with a Canon EOS 450 so that only visible light was recorded. The light of the LFC address only a few modes of the fiber. The pattern can be observed for several minutes with only minor changes.
—Philipp Huke, Georg-August-University Göttingen, Germany
20 Nov 2019