Populations and optical gain properties of Ho3+ in sulfide glasses for U-band (1625-1675 nm) fibre optic amplifiers

Abstract

Spectroscopic properties of Ho3+-doped sulfide and chalcohalide glasses were investigated for their potential for U-band fibre optic amplifiers. Emissions centered at similar to 1.67 mu m from the I-5(5)-> I-5(7) transition in Ho3+ were recorded. Population inversion was achieved between the I-5(5) and I-5(7) levels in Ho3+ with approximately 0.05 mol% Tb3+ codoping. Calculations based on cross sections and population densities show that a positive gain can be realised in the U-band region upon codoping of Tb3+.