Mid-infrared Emission Properties of Ho~(3+)-doped Ge-Ga-S-CsI Glasses

A serial of chalcogenide glasses based on Ge-Ga-S-CsI system doped with the different Ho3+ ions were synthesized by melt-quenching technique.The properties of glasses including refractive indexes,absorption spectra,mid-infrared emission spectra and lifetimes of 5I6 level of Ho3+ions were measured.The Judd-Ofelt intensity parameters Ωi(i=2,4,6),oscillator strength fcal,spontaneous transition probabilities Arad for Ho3+ ion were calculated by Judd-Ofelt theory.Multiphonon relaxation rates of the Ho3+∶5I5→5I6 and 5I6→5I7 in Ge-Ga-S-CsI glasses were evaluated.Effect of Ho3+ion concentration on the fluorescence spectra was investigated.The results indicate that the fluorescence under 900 nm excitation with peak wavelength at 2.81μm and 3.86μm are due to the Ho3+∶5I5→5I6 and 5I6→5I7 transition,respectively.The intensity of the mid-infrared fluorescence are enhanced with the Ho3+ ion concentration increasing from 0.5wt% to 1.0wt%.Multiphonon relaxation rates are 29s-1 and 34s-1 for the Ho3+∶5I5→5I6 and 5I6→5I7 transition,respectively.