in such fibers: material losses, tunneling through a finite cladding, surface-mode
coupling, and surface roughness [131, 136]. When the same synthetic processes as
those used to make low-loss telecommunications glass are employed to make the
glass in a PBGF, the material losses are predicted to be less than 0.0015 dB/km for
a mode profile with a 1% overlap with the glass. The tunneling loss of a leaky
mode through the finite number of cladding-hole layers is predicted [135] to be
less than 0.1 dB/km for 10 rows of holes with a hole diameter-to-pitch ratio of
0.95, typical of the number of rows for PBGF reported in the literature. The losses
due to surface-mode coupling to the hollow-core modes can be greater than
100 dB/km near the resonance of the ...