Fig. 2: Toy model for the shear rate on the fiber core surfaces.
From: Hollow-core fibers with reduced surface roughness and ultralow loss in the short-wavelength range
a Diagram of the transition region between the preform and the fiber. \({P}_{1}\) and \({P}_{2}\) stand for the pressure in the preform and in the fiber, respectively; \({r}_{0}\) and \({r}_{f}\) are the preform and fiber radii, respectively. \(L\) is the preform-to-fiber transition length. b Color plot of \(\frac{{\gamma }_{{eff}}}{{\gamma }_{0}}\) for varying pressure differences, \(|\Delta {P|}\), and preform-to-fiber down-ratio, \(\frac{{r}_{0}}{{r}_{f}}\). c Graph for \(\frac{{\gamma }_{{eff}}}{{\gamma }_{0}}\) as a function of \(\frac{{r}_{0}}{{r}_{f}}\) for \(\left|\Delta P\right |=5{{{{{{\rm{kPa}}}}}}}\).
