The laser heated pedestal growth (LHPG) technique is suitable to grow crystalline fibers and has been successfully applied for the general study of a lot of optical materials as laser crystals. Our general approach on the research of diode-pumped Yb3+-doped host crystals is presented through typical example of CaF2 fluoride, which is considered among the important laser crystals either for basic or applied reasons. Spectroscopic characterizations were carried out. Especially, Yb3+ (F-2(5/2)) excited level experimental decay time dependence on Yb3+ ion concentration is analyzed by using our own approach on the synthesis of a concentration gradient fiber grown in the laboratory. Our main objective is to contribute to have a better understanding of concentration quenching mechanisms not only in laser crystals but more generally in luminescent materials. (c) 2006 Elsevier B.V. All rights reserved.