Optical Properties Of Rare Earth Ions Doped Bismuth Glasses

Rare earth ions doped glasses have been widely investigated due to their potential applications in various optical devices such as solid state lasers,optical fiber amplifiers,optical communications and display.Bismuth oxide glasses have been considered to be a promising rare earth ion doped matrix material duo to its various advantages,such as high infrared transparency,high refractive index,high density,high thermal stability and low phonon energy.Bismuth germanate glasses doped with a series of different concentrations of Dy³⁺ions were synthesized using melt-quenching method.The structure and optical properties of prepared glasses were characterized through Raman spectrum,absorption spectra,excitation and emission spectra and decay curves.Results show that the prepared bismuth germanate glass network are mainly composed of[BiO3]pyramidal units,[BiO6]octahedral units and[GeO4]tetrahedral units.Besides,the prepared glasses show excellent infrared transparency and the maximum transmittance reaches 78%.Upon the excitation source of an 808nm laser diode,a flat and broad 2.9?m emission with a bandwidth of 374nm was obtained in a 1.0mol%Dy³⁺doped glass.The peak emission cross section around 2.9?m is estimated to be7.78×10^-21cm² based on the fluoresce spectrum.In addition,under the 391nm excitation,the glasses can emit white light,and the color of the luminenscence can be adjusted through doping different Dy³⁺concentration.Therefore,The prepared Dy³⁺doped bismuth gernamate glasses have potential applications in the mid-infrared solid state lasers and white light emitting devices.Tm³⁺/Dy³⁺codoped bismuth glasses were successfully prepared by conventional melt-quenching method.The fluorescence properties of glasses sample were characterized through differential scanning calorimetry curves,Raman spectrum,infrared transmittance spectrum,fluorescence spectra and decay curves.The results show that the prepared bismuth glasses have good thermal stability,low phonon energy and high infrared transmittance.With introduction of Dy³⁺ions,the intensity inversion between 1.47?m and 1.8?m emission occurred.Strong enhancement of 1.47?m emission was achieved in Tm³⁺/Dy³⁺co-doped bismuth glasses under 800nm LD excitation.A broadband emission spectrum around 1.47?m with full-width at half-maximum 118nm has been obtained in a 0.9mol%Tm³⁺and 0.3mol%Dy³⁺co-doped glass.The peak stimulated emission cross section and figure of merit for bandwidth?FWHM??_e?were calculated to be 4.37?10^-21cm² and 5.31?10^-26cm³ respectively.Results show that the prepared bismuth glass is a promising candidate for fiber amplifiers operating in S-band.Er³+/Tm³⁺codoped lead-free bismuth silicate glasses were successfully prepared by conventional melt-quenching method.The energy transfer mechanism and energy transfer efficiency between Er³⁺and Tm³⁺ions were investigated through absorption spectra and fluorescence spectra.The results show that the Tm³⁺:1.8?m emission is enhanced by codoping Er³⁺ions upon 800 nm and 1550 nm excitation.The corresponding maximum emission cross sections are estimated to be 6.7×10^-21 cm² and 7.3×10^-21 cm² on the basis of Fuchbauer–Ladenburger equation,respectively.Simultaneously,both values of 1.8?m emission bandwidth are about 250 nm.The direct energy transfer microscopic parameter of Er³⁺:⁴I_13/2?Tm³⁺:³F₄ process is calculated to be 16.8×10^-40cm⁶/s.This phenomenon results in the relatively stronger 1.8?m emission using a 1550 nm pumping source.