Optical transition properties of Yb 3+ in new fluorophosphate glasses with high gain coefficient

Abstract

A new series of 0.4MgF 2–0.4BaF 2–0.1Al(PO 3) 3–0.1Ba(PO 3) 2 glasses doped with Yb 3+ is introduced for fiber and waveguide laser applications. Spectroscopic properties including emission cross-section and lifetime and optical properties including refractive index, nonlinear refractive index, and Abbe number are reported as a function of Yb 2O 3 concentration. The refractive index n d is linearly dependent on Yb 2O 3 concentration, while the nonlinear refractive index, n 2 = 1.42 × 10 −13 esu, which is independent of Yb 2O 3 concentration, is extremely small. In addition, the Abbe number is remarkably high, >65, and is also independent of Yb 2O 3 concentration. To our knowledge, the emission cross-section σ emi, which was found to be ∼0.87 pm 2 at the lasing wavelength of 996 nm, is the highest one among fluorophosphate glasses. This glass exhibits an extremely high gain coefficient, G = 0.95 ms pm 4, and high quantum efficiency of η = 94%. The combination of outstanding spectroscopic (high emission cross-section and gain coefficient) and optical (low dispersion and small nonlinear refractive index) properties demonstrates that the current Yb 3+ activated fluorophosphate glass is an excellent candidate material for fiber and waveguide lasers.