Chalcogenide glasses are important materials for a wide range of technical applications, such as infrared optical elements, acousto-optic and all-optical switching devices, holographic recording media, diffractive optics, photonic crystals, etc. Optical investigation such as infrared reflectance and Raman spectroscopy are efficient tools for obtaining information on the local structure of the disordered material, especially when the composition is varied. In this paper we present the Raman spectra of bulk and amorphous thin films as-deposited and after light irradiation of (As₄S₃Se₃)_1-x:Sn_x (0 ≥ x ≥ 10 at. % Sn) chalcogenide glasses. The Raman spectra of (As₄S₃Se₃)_1-x:Sn_x glasses consist of two broad bands located at around v = 236 cm^-1 and v= 345 cm^-1, which corresponds to the main vibration modes of vitreous As₂Se₃ and As₂S₃. Tin impurities didn't change the shape of Raman spectra, but shift the both bands to low frequency region. The maximum situated at around v = 236 cm^-1 and v= 345 cm^-1 are characteristic for all investigated glass compositions and are attributed to the symmetric stretching vibration modes of AsSe_3/2 and AsS_3/2 pyramids, respectively. The light exposure of amorphous (As₄S₃Se₃)_1-x:Sn_x thin films shift the main maximums of Raman spectra toward the lower energies.