Site-selective study of Nd3+ optical centers in Ca3Sc2Ge3O12 laser garnet crystals

Abstract

The Nd3+ multicenter distribution in a Ca3Sc2Ge3O12 garnet laser crystal has been analyzed by low temperature site-selective laser spectroscopy. Two nonequivalent Nd3+ centers have been identified and characterized in this host lattice. The effect of codoping the crystal with MgO on the Nd3+ center distribution has also been investigated, since this codoping enables considerable enhancement of the doping levels of these crystals. Three different centers were observed in the codoped crystals, together with a reduction of inhomogeneous emission broadening. The nature of the optical centers present in both cases is discussed by considering the charge compensation mechanisms involved in accommodation of Nd3+ ions.

Optical spectra of Dy3+-doped GdVO4 and Ca3Sc2Ge3O12 crystals and evaluation of the Ω2/Ω6 ratio as a quality factor for the classification of Dy3+-activated crystalline hosts

“…As anticipated in the previous section in fact, the substitution of Dy 3þ for Ca 2þ requires charge compensation, which can be obtained in a number of ways: formation of cationic vacancies, addition of suitably charged ions, etc., depending on some experimental solutions adopted in the growth procedure. Whatever the case is, the consequence is that in addition to Dy 3þ ions located at regular (unperturbed) Ca 2þ sites, there will be also ions located in sites perturbed by the presence of vacancies or aliovalent ions in the second coordination sphere, then experimenting slightly different crystal fields and having slightly but appreciably different optical behaviours [11]. The spectrum of GVO:Dy shows limited polarization effects, that have been properly taken into account in the fitting procedure.…”