Highly Efficient 2.84- $mu ext{m}$ Emission in Ho3+/Yb3+ Co-Doped Tellurite–Germanate Glass for Mid-Infrared Laser Materials

The use of Yb3+ co-doping with Ho3+ to enhance the Ho3+: 5I6 → 5I7 ~ 2.84-μm emissions is investigated in the tellurite-germanate glasses. An intense ~ 2.84-μm emission with a full width at half maximum (FWHM) of 132 nm is achieved in the Ho3+/Yb3+ co-doped tellurite-germanate glass upon excitation at 980 nm. The glass not only possesses considerably low OH- absorption coefficient (0.206 cm$^{-1}$...