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

Abstract Bi-doped and Yb–Bi-codoped SiO 2 –Al 2 O 3 –CaO glasses were prepared, and the effect of Al 2 O 3 composition on the near-infrared (NIR) emission and energy transfer between Yb 3 + and Bi n + (Bi NIR emission centers) were investigated. The introduction of Al 2 O 3 into the glass hosts can vary the NIR luminescence centered at 1300 nm and obtain the strongest emission when the concentration of Al 2 O 3 is 15 mol%. Efficient energy transfer from Yb 3 + to Bi n + is achieved by co-doping of Al 2 O 3 . With the increased Al 2 O 3 concentration, the energy transfer efficiency between Yb 3 + and Bi n + increased at first and then decreased, maximizing (~ 79%) at 8 mol%. It is suggested that the introduction of appropriate Al 2 O 3 concentration in Yb–Bi-codoped silicate glasses may be an efficient way to realize effective optical amplification with commercially available 976 nm LD pumping.