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

Abstract

Abstract-We grew good-optical-quality KGd(WO 4 ) 2 single crystals doped with erbium and ytterbium ions at several concentrations of dopants using the top-seeded-solution growth slow-cooling method (TSSG). We performed the spectroscopic characterization of this material related to the 1.5-m infrared emission of erbium which is interesting for laser applications. To do this, we carried out polarized optical absorption at room temperature (RT) and at low temperature (6 K) and performed luminescence studies of the emission and lifetime. We obtained the 1.5-m emission of erbium after selective laser pump excitation of the ytterbium ion and energy transfer between the two ions. The maximum emission cross section for 1.5 m was about 2 56 10 20 cm 2 for the polarization of light with the electric field parallel to the principal optical direction. This value was higher than for other erbium-doped materials with application in solid-state lasers such as LiYF 4 : Er(

High optical gain in erbium-doped potassium double tungstate channel waveguide amplifiers

“…Optical losses have limited the widespread application of integrated-optical circuit chips. The aim to compensate these losses has fueled the demand for on-chipintegrated host materials with erbium concentrations exceeding 10 20 cm −3 to increase the gain in EDWAs. Low dopant solubility, which causes Er 3+ clusters, is a major obstacle to increasing the erbium density in glass hosts.…”

Potassium double tungstate waveguides with high ytterbium concentration for optical amplification

“…The absorption spectra of KLu0.24Yb0.76(WO4)2 and KGd0.43Yb0.57(WO4)2 shown in Figure 4.9 are found to be very similar to those of KGd(WO4)2:Yb 3+ [73,114], KLu(WO4)2:Yb 3+ [107], and KYb(WO4)2 [106]. They are in excellent agreement with that of KY(WO4)2:Yb 3+ * [71], especially at the peak absorption value near 981 nm.…”

“…The epitaxial layer growth technique and waveguide structuring technique had also been used to realize high gain Yb 3+ -activated [20] [59,[70][71][72][73][74]. Thirdly, the use of co-doped Gd 3+ and Lu 3+ in the layer allows the growth of high Yb 3+ concentration layer with refractive index contrast of ~0.01-0.02 with respect to the substrate [65].…”

“…The spectroscopic properties of potassium rare-earth double tungstates doped with trivalent ytterbium, KRE(WO4)2:Yb 3+ , were reported as early as 1997 by Kuleshov et al [71,123]. Thereafter, numerous studies were performed on bulk crystals of KGd(WO4)2:Yb 3+ [71,73], KLu(WO4)2:Yb 3+ [74,107], KY(WO4)2:Yb 3+ [71] and KYb(WO4)2 [104,106]. On the other hand, comprehensive spectroscopy studies on KRE(WO4)2:Yb 3+ epitaxial layers [107,124] are relatively scarce.…”

“…Hence, it is reasonable to assume that the influence of neighboring transitions is negligible and the temperature dependence of these major absorption peaks can be approximated from Equation 2.24 which is reproduced as follows, . The values deviate by less than 2.5% if any of the other sets of level energies of KGd(WO4)2:Yb 3+ [73], KLu(WO4)2:Yb 3+ [74] or KYb(WO4)2 [104] is chosen. When the temperature increases from 20 °C to 170 °C, the value of f00 is reduced by ~18%.…”