Tetravalent chromium doped laser materials and NIR tunable lasers

摘要

A method is described to improve and produce purer Cr.sup.4-doped laser materials and lasers with reduced co-incorporation of chromium in any other valence states, such as Cr.sup.3, Cr.sup.2, Cr.sup.5, and Cr.sup.6. The method includes: 1) certain crystals of olivine structure with large cation (Ca) in octahedral sites such as Cr.sup.4:Ca.sub.2GeO.sub.4, Cr.sup.4:Ca.sub.2SiO.sub.4, Cr.sup.4:Ca.sub.2Ge.sub.xSi.sub.1-xO.sub.4 (where 0<x<1), and/or 2) high-temperature solution growth techniques that enable the growth of the crystals below the temperature of polymorphic transitions by using low melting point solvent based on oxide, fluoride and/or chloride compounds. Purer Cr.sup.4-doped laser materials are characterized by a relatively high concentration of Cr.sup.4-lasing ion in crystalline host that makes these materials suitable for compact high power (thin disk/wedge) NIR laser applications.