In this study Yb-doped Y<sub>2</sub>SiO<sub>5</sub> single crystals and thin films crystal field excitations and Raman active phonons
characteristics have been compared using infrared absorption and Raman spectroscopy. The thin films high
quality has been confirmed and their ability to adjust by co-doping various properties such as the Yb<sup>3+</sup> sites
occupations and Yb<sup>3+</sup>-Yb<sup>3+</sup> pair interactions have been evidenced.