According to the originating NASA/UAH paper[1], where they took a fiber-making machine into their microgravity-simulating plane, gravity causes tiny amounts of

According to the originating NASA/UAH paper[1], where they took a fiber-making machine into their microgravity-simulating plane, gravity causes tiny amounts of convection inside the molten fiber. That's why you can't just float the fiber on air or something. Their guess is that the convection creates tiny little circular currents in the glass that are really excellent at causing crystal nucleation. The core problem is that ZBLAN glass needs to be cooled down very quickly to solidify in the amorphous state. Drawing a fiber demands that you do it quite slowly to get a quality, consistent fiber. Drawing is not a technology that is going to improve hugely any time soon- it's too fundamental. Instead you need the microgravity to give you a little extra time to draw the fiber to the required quality. [1]: https://www.researchgate.net/publication/8087775_Effects_of_Gravity_on_ZBLAN_Glass_Crystallization https://www.researchgate.net/publication/8087775_Effects_of_...