Efficient 2.0 μm emission in Nd3+/Ho3+ co-doped tungsten tellurite glasses for a diode-pump 2.0 μm laser

We report on an efficient 2.0 μm emission from Ho3+ via Nd3+ sensitization in tungsten tellurite glasses upon excitation with an 808 nm laser diode. The underlying mechanism is analyzed by means of photoemission spectroscopy and lifetime measurement. Judd-Ofelt intensity parameters, radiative properties, and emission cross section of Ho3+ are evaluated. Nd3+ with high absorption cross section near 808 nm (2.64 × 10−20 cm2) plays an important role in 2.0 μm emission by transferring pump energy to Ho3+:5I5 level. Meanwhile, only very weak upconversion are obtained. The use of Nd3+ as a sensitizing ion could open up a possibility to realize high efficient 2.0 μm lasing from Ho3+, which could operate at an 808 nm diode laser pump.