LD end-pumped composite Tm/Ho: YAP laser

Ho laser operation in a composite Tm/Ho: YAP gain medium is demonstrated for the first time, which is integrated via diffusion bonding the Tm-doped and Ho-doped into a single bulk YAP crystal. A laser diode with central wavelength of 795 nm, which is the absorption peak of Tm3+ ion, is used as the pumping source. At absorbed pump power of 22 W, maximum output power of 4.9 W at 2010.8 nm with a power instability of 0.61 % is achieved. The corresponding slope efficiency of 28.6 % and the optical conversion efficiency of 22.4 %. The beam quality is measured to be with M2 of 1.25 and 1.21 in the horizontal and vertical directions, respectively.