Abstract

Cr:Sr₃Ga₂Ge₄O₁₄ crystal is a new tunable laser material with a tunable range from 810 nm to 1250 nm (⁴T₂→⁴A₂ channel), which is one of the longest tunable wavelength in Cr³⁺-doped materials. Single crystals of Cr:Sr₃Ga₂Ge₄O₁₄ garnets are grown by the Czochralski method in air. The polarized optical absorption spectra of Cr are measured. The schematic description on the absorped bands in visible and near-infrared wavelength are presented in Fig. 1. It's suggested that Cr enters the octahedral and tetrahedral positions as Cr³⁺ and Cr⁴⁺ respectively. The near-infrared absorption bands of Cr⁴⁺ will affect the luminescence of Cr³⁺. The figure of merits (FOM) of Cr³⁺ ions is α_{433.6 nm}/α_{1056 8 nm} = 34. Clearly, the elimination of the residual near-infrared absorption of the Cr:Sr₃Ga₂Ge₄O₁₄ crystal is very important for 810-1250 nm laser output.

© 1995 IEEE