| 摘要 |
A method is described to improve and produce purer Cr<SUP>4+</SUP>-doped laser materials and lasers with reduced co-incorporation of chromium in any other valence states, such as Cr<SUP>3+</SUP>, Cr<SUP>2+</SUP>, Cr<SUP>5+</SUP>, and Cr<SUP>6+</SUP>. The method includes: 1) certain crystals of olivine structure with large cation (Ca) in octahedral sites such as Cr<SUP>4+</SUP>:Ca<SUB>2</SUB>GeO<SUB>4</SUB>, Cr<SUP>4+</SUP>:Ca<SUB>2</SUB>SiO<SUB>4</SUB>, Cr<SUP>4+</SUP>:Ca<SUB>2</SUB>Ge<SUB>x</SUB>Si<SUB>1-x</SUB>O<SUB>4 </SUB>(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+</SUP>-doped laser materials are characterized by a relatively high concentration of Cr<SUP>4+</SUP>-lasing ion in crystalline host that makes these materials suitable for compact high power (thin disk/wedge) NIR laser applications.
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