Abstract

Hypothesis of Cr⁴⁺ active centers of forsterite substituted for tetrahedrally coordinated Si ions first was described in [1]. This Model admitted by most of the investigators is still the problem to be discussed. So some authors [2—4] consider that there are few experimental data to give the only explanation of nature of lasing center in forsterite. Indeed, using exclusively optical methods, in particular, without EPR, it is impossible, in principal, to prove strictly that Cr ions are lasing ions. Last conference we reported [5] the results of EPR investigations and EPR relaxometry with selective laser excitation on the basis of which we could attribute the excitation spectra of 1.25 mm luminescence to Cr⁴⁺ in tetrahedral coordination. It was directional experimental proof of Cr⁴⁺ hypothesis. However, the lack of complete understanding spectral characteristics of forsterite especially of various energy transfer processes and ion—ion interactions makes us again and again to look for additional experimental proofs of origin lasing in chromium-doped forsterite.

© 1992 Optical Society of America