Judd–Oflet analysis of spectrum and laser performance of Ho:YAP crystal end-pumped by 1.91-μm Tm:YLF laser

The Ho:YAP crystal is grown by the Czochralski technique. The room-temperature polarized absorption spectra of Ho:YAP crystal was measured on a c-cut sample with 1 at% holmium. According to the obtained Judd–Ofelt intensity parameters Ω 2 = 1.42 × 10 −20 cm 2 , Ω 4 = 2.92 × 10 −20 cm 2 , and Ω 6 = 1.71 × 10 −20 cm 2 , this paper calculated the fluorescence lifetime to be 6 ms for 5 I 7 → 5 I 8 transition, and the integrated emission cross section to be 2.24 × 10 −18 cm 2 . It investigates the room-temperature Ho:YAP laser end-pumped by a 1.91-μm Tm:YLF laser. The maximum output power was 4.1 W when the incident 1.91-μm pump power was 14.4W. The slope efficiency is 40.8%, corresponding to an optical-to-optical conversion efficiency of 28.4%. The Ho:YAP output wavelength was centred at 2118 nm with full width at half maximum of about 0.8 nm.