Optimized combination of Ho3+ and sulfide glass for U-band fiber-optic amplifiers

Spectroscopic properties of 1.6 μm emission from Ho3+-doped sulfide glass were evaluated for their potential use as U-band fiber-optic amplifiers. Emission from the 5I5 → 5I7 transition showed a peak wavelength of 1670 nm and a full width at half maximum of ∼65 nm with a cross-section of ∼7.1 × 10−21 cm2. Ho3+ concentration in glass should be limited to 0.08 mol% due to energy transfers between Ho3+ ions which lead to a decrease in the 5I5 level lifetime. Co-doping of Tb3+ effectively decreased terminal 5I7 level lifetimes via the energy transfer of Ho3+:5I7 → Tb3+:7F0, 1, 2.