Studies on a novel Ho3+:KBGM crystal toward the ∼2 μm laser applications

A Ho 3+ :KBGM crystal with good quality and large size was successfully grown via TSSG method. The crystal’s structure, ambient-temperature polarized absorption and emission spectra and fluorescence lifetime were studied. The J-O theory was adopted to analyze the absorption spectra and results show that crystal exhibits relatively large intensity parameters Ω 2 and spectroscopic quality factor which is up to 3.12. At 453 nm, the absorption band is the strongest, and the corresponding cross-sections are 21.94 × 10 –20 cm 2 , 26.66 × 10 –20 cm 2 and 18.56 × 10 –20 cm 2 for the - X , - Y and - Z polarizations, respectively. The emission spectra also demonstrate the broad and strong emission band at 2030 nm. The FWHMs and cross-sections are 74 nm, 0.37 × 10 −20 cm 2 , 50 nm, 0.68 × 10 −20 cm 2 , and 49 nm 0.52 × 10 −20 cm 2 for the three polarizations, respectively. In addition, the crystal has a superior quantum efficiency which is as high as 97.1%. Taking all the analyses into account, it is reasonable to assert that the Ho 3+ :KBGM crystal an ideal candidate for ∼2 µm laser applications in many areas.