Samarium-doping concentration influence on spectroscopic parameters of Sm: YAG crystal
The main goal of this work was to characterize the spectroscopic properties (absorption, fluorescence, and lifetime) of the samarium ion in the yttrium-aluminum-garnet matrix. The Sm:YAG crystals with various samarium concentrations (1, 3, 6.4, 10, and 20 at.% Sm/Y in the melt) were produced by the edge-defined, film-fed growth technique. Absorption characteristics were investigated in the spectral range of 185 – 3100 nm with detailed measurements in the near-infrared range of 1058 to 1125 nm, corresponding the energy level transition 6H5/2 → 6F9/2. The results indicate that the specific absorption properties of the Sm:YAG crystal could be advantageously used to an absorption of parasitic fluorescence around 1064 nm, generated by Nd:YAG laser. Concerning emission dependencies in a visible spectral region from 520 to 850 nm, a dominant peak was observed at 618 nm. In the infra-red spectral range from 850 to 1450 nm the dominant peak was found at the wavelength of 1231 nm. From the 4G5/2 level lifetime measurements, the dependence of lifetime on the samarium ions concentration in the YAG matrix was proven. Lifetime values ranged from 0.2 (20 at.% Sm/Y) to 2.0 ms (1.0 at.% Sm/Y). From the spectroscopic results it follows that the Sm:YAG crystal is a suitable candidate for attenuation of an unwanted spontaneous radiation at 1064 nm wavelength of the Nd:YAG laser or for lightconversion from UV to yellow-red visible region.