EN
Optical-temperature investigations of stationary and photo-induced absorption in undoped and Al (or Ga) doped Bi₁₂SiO₂₀ crystals are discussed. In the wave-number range 22000-4000 cm¯¹ under temperatures from 80 to 650 K, peculiarities of thermochromic effect have been revealed and temperature dependences of intensity of bands forming photo- and thermochromic effects have been found. A correlation between these dependences and spectra of thermostimulated current is explained.