Effects of Al2O3 composition on the near-infrared emission in Bi-doped and Yb–Bi-codoped silicate glasses for broadband optical amplification

Bi-doped and Yb–Bi-codoped SiO2–Al2O3–CaO glasses were prepared, and the effect of Al2O3 composition on the near-infrared (NIR) emission and energy transfer between Yb3 + and Bin + (Bi NIR emission centers) were investigated. The introduction of Al2O3 into the glass hosts can vary the NIR luminescence centered at 1300 nm and obtain the strongest emission when the concentration of Al2O3 is 15 mol%. Efficient energy transfer from Yb3 + to Bin + is achieved by co-doping of Al2O3. With the increased Al2O3 concentration, the energy transfer efficiency between Yb3 + and Bin + increased at first and then decreased, maximizing (~ 79%) at 8 mol%. It is suggested that the introduction of appropriate Al2O3 concentration in Yb–Bi-codoped silicate glasses may be an efficient way to realize effective optical amplification with commercially available 976 nm LD pumping.