Interesting diffraction pattern coming from an exposed optic fibre port. Didn't notice it at the start, but it looks like you can see the 8 separate beams coming through, with the main light down the middle as scattered waves.
Still thinking about the ring pattern of the glow. The light should be of the same wavelength so there shouldn't be any interference. Might be just the difference between light bouncing off the top of the glass rather than the bottom when exiting. You would think that the scattered light would have travelled different distances within the core though, so their starting wave positions should be averaged out. That would lead to an averaged difference pattern too, which would mean a more or less constant light.
