High Efficiency Continuous-Wave Tm:Ho:GdVO₄ Laser Pumped by a Diode

We report a high efficiency cw diode-pumped cryogenic Tm(5at.%), Ho(0.5at.%):GdVO₄ laser. The pumping source is a fibre-coupled laser diode with fibre core diameter of 0.4mm and numerical aperture of 0.3, supplying power 14.8W at 793.6nm. For input pump power of 13.6W at 794.2nm, the maximum output power of 4.2W, optical-to-optical conversion efficiency of 31% and slope efficiency 38% have been attained at 2.0485μm. To our knowledge, the operating performance is the best among the previously reported Tm:Ho:GdVO₄ lasers. We also analyse the influence of pump wavelengths (from 792 nm to 794.2 nm) on the output power, the optical-to-optical conversion efficiency increases with the longer pump wavelength which is closer to the absorption peak of 797 nm in Tm,Ho:GdVO₄.