It certainly does interfere with itself. Light doesn't interact (in the sense of particles hitting each other) with itself. In fact the only time interference occurs is when indistinguishable particles (photons) interfere with the 2 or more different routes they COULD HAVE TAKEN. All particles can interfere, and they all can interfere only with themselves.

I'm busy trying to get my head around, why partially reflecting laser light back into the laser, induces a chaotic signal. It doesn't seem right, there's a laser frequency and two reflection distances, (remember lasers have a mirror at each end). It doesn't seem complex enough to be chaotic.

If it is chaotic and you believe in the Everett Interpretation, they've just produced the worlds fastest world splitter.