Efficient O-band emission from Pr³⁺ doped low phonon energy ZnF₂-based glasses

Pr³⁺ doped ZnF₂-based (ZnF₂-BaF₂-SrF₂-YF₃) glasses with a low phonon energy of ∼420 cm⁻¹ are prepared by using a conventional melt-quenching method in dry N₂ atmosphere. Under the excitation of a 980 nm laser diode, intense emission at ∼1310 nm is observed from the Pr³⁺ doped ZnF₂-based glasses. The full spectral width at half maximum is 107 nm (1275–1382 nm), which is ∼7 nm wider than that of Pr³⁺ doped ZrF₄-based glass (∼100 nm, 1279–1379 nm). The measured lifetime (∼183 μs) of the excited energy level ¹G₄ for Pr³⁺ ions in the ZnF₂-based glass is also much longer than that of Pr³⁺ doped in ZrF₄-based glass (∼110 μs). According to the theoretically calculated results, a positive gain of 31.7 dB at 1304 nm can be obtained from O-band optical amplifiers based on the Pr³⁺ doped ZnF₂-based glass, which is 5 dB higher than that obtained from amplifiers based on Pr³⁺ doped ZrF₄-based glass with a same pump condition. The corresponding bandwidth for a net gain of >20 dB is ∼51 nm (1277–1328 nm), and the noise figure is calculated to be < 5.8 dB in above spectral range. Our results indicate that Pr³⁺ doped ZnF₂-based glasses have the potential for constructing efficient O-band optical amplifiers.