Growth, Thermal, and Optical Properties of a Novel Mid-Infrared Ho:LuYAP Laser Crystal

Abstract

A novel mid-infrared Ho:Lu 0.1 Y 0.9 AlO 3 laser crystal with a size of Φ26 mm × 80 mm was grown successfully by the Czochralski method. The crystal structure was characterized in detail by powder and single-crystal X-ray diffractions: Pnma (62) space group, a = 5.3234 Å, b = 7.3517 Å, c = 5.1670 Å, V = 202.22 Å 3 , and Z = 1. The X-ray rocking curves show that the crystal possesses high crystalline quality. It was observed by a transmission electron microscope that all atoms are neatly arranged and all elements are uniformly distributed. Meanwhile, the refractive index curves from 400 to 3000 nm at three crystalline axes and Mohs hardness were also achieved. The thermal expansion coefficient is 4.382 × 10 −6 K −1 , and thermal conductivity is 5.872 W•m −1 •K −1 . Particularly, the maximum phonon energy is only 552 cm −1 , as exhibited by the Raman spectrum. Finally, the transmission, fluorescence spectra, and level lifetimes were measured and compared, which provided a basis for subsequent spectral theoretical analysis and laser experiment.