Spectroscopic properties of LiGa5O8 single crystals doped with chromium

Spectroscopic parameters of chromium-doped lithium-gallium spinel crystals are studied in the temperature range from 77 to 300 K. It is found that optical absorption and luminescence of crystals are related to Cr3+ ions located in octahedral positions with the local symmetry C-3v. The energy level diagram of Cr3+ ions calculated using the crystal-field theory is in good agreement with experimental data. Room-temperature stationary induced absorption spectra of crystals exhibit strong absorption in the 400-700-nm region, which was assigned to transitions from the excited metastable E-2 State to the levels located in the 30000-36500-cm(-1) region. The broadband absorption from the excited metastable E-2 State causes great losses in the pumping channel, so that lasing of Cr3+ ions in LiGa5O8 crystals at room temperature is unlikely.