
9.3.3 Antimony-Doped Fibers
A standard NA antimony (Sb) doped silica optical fiber was developed by Oh
et al. [25]. The RIP and the index difference (Dn) between the core and cladding were
similar to the SSMF. In D
2
-loaded samples, they observed UV photosensitivity
with an initial refractive index growth rate six times higher than in SSMF. The fiber
core diameter was 8.5 mm and the Sb
2
O
3
concentration was 3.5 mol%. The attenu-
ation at 1550 nm was 700 dB/km, which is very high, and it was attributed mainly
to the OH absorption induced in the wet sol-gel process. Antimony is a promising
element, but the background losses problem would need to be solved. ...