Optical and Magnetic Resonance Investigations of 3d Ions in Single Crystal Hosts:Candidates for Tunable Solid-State Lasers

摘要

A comprehensive report is presented on EPR and correlated optical spectroscopicstudies conducted in our laboratory on a new class of solid-state materials with potential utility as near IR lasers. All of the studied materials involve oxide host lattices (Silicates, vanadates, and germanates) doped with 3d transition metal-ions (chromium and manganese). The novelty of the materials is connected to the tetrahedral coordination and unusual oxidation state of the dopant ions. EPR spectroscopy is to determine the elemental identity of the dopant ions, the 'spin' of the ions and hence their oxidation numbers, and the crystallographic position of the ion hence its coordination number. These properties are then attached to relevant optical centers through magnetic resonance correlated optical spectroscopies, such as optical Zeeman spectroscopy. In the Cr:forsterite laser system, our results prove that the near IR lasing center is tetrahedral Cr3(+). In Mn:Ba3(VO4)2 EPR spectroscopy shows that tetrahedral Mn5(+) and Mn4(+) centers are both present in the material; a novel spin-echo pulsed laser double resonance method is introduced to prove that the tetrahedral Mn5(+) is the active center.