Differential-temperature analysis (DTA), Raman and luminescence spectroscopy were used to investigate the physical-chemical and optical properties of glassy systems doped with rare-earth ions. The glass-forming regions in the systems were analyzed for the creation of an efficient optical amplifier. The analysis showed that chalcogenide glasses possess low maximum phonon energy, high refractive index, good solubility of rare-earth ions and high chemical and thermal stability. It is suggested that low phonon energy and high refractive index of chalcogenides provides multi-phonon relaxation and high radiative transition probabilities responsible for increasing the luminescence efficiency.