Experimental demonstration of the first controlled gradient doped ytterbium YAG crystal boules grown via modified Horizontal Direct Crystallization technique is presented. Yb(3+):YAG crystals extracted from these boules exhibit a controlled continuous doping gradient, offering opportunities to explore laser concepts with greatly improved characteristics such as thermal and amplified spontaneous emission management; but also in terms of gain medium volume requirements. The growth process with its specificities compared to known growth techniques used for homogeneously doped crystal growth, is described in detail. The Yb(3+) ions distribution within the extracted crystals is quantified. Optical transmission and fluorescence measurements will also be presented. (C) 2011 Published by Elsevier B.V.