Comment on "Design of a broadband highly dispersive pure silica photonic crystal fiber" by Subbaraman et al

In a recent paper, Subbaraman et al report a theoretical and numerical study of highly dispersive pure silica photonic crystal fiber supporting group-velocity dispersion exceeding -2*10^4 ps/nm/km. This comment argues that the authors only consider one out of the two sides of the same coin, by not taking the corresponding beating length into account.