Sensitization ofEr3+emission at1.5μmby

Xavier Mateos

¹

,

M. C. Pujol

²

,

Frank Güell

³

et al.

Abstract

We present our recent achievements in the growth and spectroscopic characterization of KYb(WO 4 ) 2 crystals doped with erbium ions ͑hereafter KYbW:Er͒. We grew single crystals of KYbW:Er at several erbium concentrations with optimal crystalline quality by the top-seeded-solution growth ͑TSSG͒ slow-cooling method. We carried out spectroscopic measurements related to the polarized optical absorption and optical emission at room temperature ͑RT͒ and low temperature ͑6 K͒. The splitting of the excited energy levels and the ground energy level of erbium in KYbW were determined, derived from the absorption and emission measurements at 6 K, respectively. We determined the near infrared, around 1.5 m (6667 cm Ϫ1 ), emission channels from the emission spectrum, and used the reciprocity method to calculate a maximum emission cross section of 2.7ϫ10 Ϫ20 cm 2 for the polarization parallel to the N m principal optical direction for the 1.534 m (6519 cm Ϫ1 ) infrared emission. We measured the lifetime of the 2 F 5/2 → 2 F 7/2 transition of ytterbium and the 4 I 13/2 → 4 I 15/2 transition of erbium at RT for several erbium concentrations. Finally, we present the Judd-Ofelt calculations for the KYbW:Er system.

Erbium spectroscopy and 1.5-/spl mu/m emission in KGd(WO/sub 4/)/sub 2/: Er,Yb single crystals

“…The splitting in KYbW crystals was slightly greater than in KGW crystals, showing that the crystal field of KYbW was stronger than in KGW, which agrees well with the fact that the interatomic distances Yb-Yb in KYbW were smaller than the corresponding Gd-Gd distances in KGW [9], [21], [22]. Also, the previously calculated Judd-Ofelt parameters of erbium in KYbW [19] and in KGW [10], showed the influence of this crystal field, where the Judd-Ofelt parameters of KYbW were larger than those of KGW.…”

“…We later used this energy difference to calculate the splitting of the ground energy level. These values are similar to those for erbium in similar materials, such as KYbW:Er [19], KGW:Er [10], and KYW:Er [20].…”

“…We compared the splitting of each energy level into its sublevels of erbium in KGW with the splitting found previously in KYbW:Er [19]. The splitting in KYbW crystals was slightly greater than in KGW crystals, showing that the crystal field of KYbW was stronger than in KGW, which agrees well with the fact that the interatomic distances Yb-Yb in KYbW were smaller than the corresponding Gd-Gd distances in KGW [9], [21], [22].…”

Preparation, thermal stability and magnetic properties of new AgY1−xGdx(WO4)2 ceramic materials

“…High physical and optical anisotropy resulting from low symmetry structure, possibility of high doping levels due to close ionic radii without luminescence quenching and significant lattice distortions as well as a wide range of laser emission, i.e. $ 1 μm for Yb 3 þ , and $ 2 μm for Ho 3 þ and Tm 3 þ ions are the advantages of these materials [23][24][25][26][27][28][29][30][31][32][33]. Physical properties of alkali and trivalent rare earth double molybdates and tungstates both single crystals and powders were analyzed by many authors [34][35][36][37][38][39][40][41][42].…”

Ultraviolet and visible emissions of Er3+ in monoclinic KYb(WO4)2 single crystals

“…We also doped KYbW crystals with Er 3+ ions at several dopant concentrations to characterize the potential laser transitions. Crystal growth data and optical characterization of the visible green and infrared 1.5 m emissions of erbium in KYbW:Er have been published in [11,12]. The most important features of the KYbW host doped with Er 3+ are, firstly, that the high quantity of Yb 3+ ions also with the very large absorption cross-section can efficiently transfer the pump energy to Er 3+ thus increasing the emission intensity in the UV-vis region, secondly, that due to the similar nature of the ions, concerning charge and size, it makes possible easy substitution in the host without introducing high changes in the crystal quality, and finally, that the transitions (absorption and emission) cross-sections in such tungstates are very large, so that the requirements of the pump beam quality is reduced, favoring the pump with diodes.…”