Yb:NaGd(WO4)2: spectroscopic characterisation and laser demonstration

Here, Yb:NaGd(WO₄)₂ (Yb:NGW) is presented, which - in contrast to the potassium tungstates - can be grown by the Czochralski-technique and exhibits even larger Yb-Yb-distances. The effect of radiation trapping is largely excluded due to the used experimental technique, i.e. the so-called pinhole-method. Furthermore, Yb:NGW has been tested in first laser experiments. Under titanium sapphire laser pumping, a slope efficiency of 36% and a maximum output power of nearly 200 mW were achieved. Using a diode laser at a wavelength of 975 nm a slope efficiency of 20% and a maximum output power of 230 mW were obtained.