calculated cutoff wavelength was 1375 nm. The In
2
O
3
concentration was about
0.05 mol%, and the GeO
2
was about 9 mol%. The fiber exhibited a refractive
index modulation of 3:2 10
4
. Annealed FBGs in this fiber type survived a
high temperature of 900 8C for 24 hours and even 1000 8C for more than 2 hours.
Unfortunately, the background loss was not reported by the authors, but the
brown color of the core suggests it might be quite high. This specification needs
improvement to classify indium as a good photosensitive element.
There are numerous applications for HNA fibers in areas such as filters,
narrow-band reflectors for fiber lasers, optical strain/temperature sensors, and
modal couplers. HNA fibers are also perfectly suitable to adapt the cladding ...