Chromium-doped scandium gallium garnet crystals as active media of lasers utilizing Ho3+ and Tm3+ infrared transitions

An investigation was made of the luminescence spectra of yttrium scandium gallium garnet crystals activated with Cr³⁺, Ho³⁺, and Tm³⁺ ions. Measurements were made of the excited state lifetime of Ho³⁺ and Tm³⁺. Efficient Cr→Ho and Cr→Tm nonradiative energy transfer was observed. The existence of energy transfer mechanisms having a shorter range than the dipoledipole one was established. The microscopic constants of dipole-dipole interaction were determined. It is concluded that efficient Cr→Ho and Cr→Tm energy transfer suggests that efficient room-temperature lasers may be developed utilizing infrared transitions in these rare-earth ions.