Color centers in Yb:YAG crystals grown by temperature‐gradient techniques

Abstract

Yb:YAG (Yb:Y3Al5O12) crystals have been grown by temperature‐gradient techniques (TGT) and their color centers and impurity defects were investigated by means of gamma irradiations and thermal treatment. Two color centers located at 255 and 290 nm were observed in the as‐grown TGT‐Yb:YAG. Analysis shows that the 255 nm band may be associated with Fe3+ ions. Absorption intensity changes of the 290 nm band after gamma irradiation and thermal treatment indicate that this band may be associated with oxygen‐vacancy defects. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Influence of Gamma-Ray Irradiation on Absorption and Fluorescent Spectra of Nd:YAG and Yb:YAG Laser Crystals

“…In addition, most of the literature has also focused on the type of colour centre and formation mechanism of Yb:YAG crystal after gamma irradiation. [10,11] However, the influence of gamma irradiation on the fluorescent properties of Yb:YAG crystals have not been reported so far. In this Letter, compared with Nd:YAG crystal, the changes of absorption and fluorescent spectra caused by gamma irradiation are investigated.…”

“…A broad positive AA band (located at 340 nm) and a sharp negative AA band (located at 255 nm) are observed on both the crystals. Dong et al [10,11] reported that the negative AA band at 255 nm is correlated with Fe 3+ ions and the broad AA band centred at 340 nm is correlated with Fe 2+ ions and F-type centres. This is due to the fact that Nd:YAG and Yb:YAG crystals were grown in oxygen absent atmosphere, leading to many oxygen vacancies produced in the as-grown crystals.…”

“…This process may be expressed as V O + e − → F + ; F + + e − → F. In addition, Fe 3+ ions would also capture free electrons to form Fe 2+ by Fe 3+ +e → Fe 2+ . [10,11] Therefore, the decreasing concentration of Fe 3+ ions leads to the negative AA value appearing at 255 nm, the increasing concentrations of Fe 2+ and F-type centres lead to generation of the positive AA band at 340 nm. As also shown in Fig.…”