Abstract:

A kind of Er³⁺ /Yb^{3 +}co-doped TeO₂ -GeO₂ - Bi₂ O ₃ -K₂ O glass was fabricated by means of the melting method , and the absorption and upconversion spectra of the glass were obtained by differential thermal analysis.Judd-Ofelt theory was then used to calculate the three strength parameters of the glass , the oscillator strength , the spontaneous radiated transition probability , the fluorescence-branching ratio and the radiation life of each energy level of Er^3+. Moreover , the green fluorescent emissions centering at 522 and 546 nm and the red fluorescent emi-ssion at 658 nm were obtained under the laser diode excitation at 977 nm , which respectively corresponded to the transitions²H _11/2 →⁴I_15/2、⁴S_3/2→⁴I _15/2 and ⁴F_9/2→⁴I_15/2 of Er^{3 +} .It is found that the strong green and red emissions all result from a two-photon absorption process.

Key words: germanium tellurite bismuth potassium glass, Er³⁺ /Yb^{3 +}co-doping, Judd-Ofelt theory, upconversion