A new laser crystal, Cr3+:LiSrGaF6 (chromium: lithiumstrontium gallium fluoride), which is potentially superior toCr3+:LiSrAlF6 (the aluminum analog), will be evaluated for use intunable laser systems which can operate from approximately 250 to400 nm. Cr3+:LiSrAlF6 is currently the only crystal that canchallenge titanium: sapphire as a broadly tunable, near-infraredlaser source. The LiSrAlF6 materials and their isomorphs have anadvantage in their potential use in rugged and compact,all-solid-state lasers, since they can be efflciently pumped bydiode lasers. However, it is not clear that the state-of-the-artdiode pumped Cr3+:LiSrAlF6 laser is the preferred source.Negligible passive loss, coupled to its potentia]ly superiorthermo-mechanical and thermo-optical properties, makeCr3+:LiSrGaF6 a worthwhile material to investigate. Cr3+:LiSrGaF6will initially be characterized using samples already available.This crystal can be grown with practically zero passive loss andin a large boule size when a novel synthesis procedure is used.This same synthesis procedure will be used for Cr3+:LiSrAlF6 toreduce its passive losses to the same level as those measured forCr3+:LiSrGaF6 crystals. In Phase I, direct comparison ofCr3+:LiSrAlF6 and Cr3+:LiSrGaF6 will be completed in order todetermine which material is more robust and better suited for theapplication. Phase I will also develop a second criticalcomponent, antireflective coatings, which are capable ofwithstanding the rigorous temperature cycling required fortunability and frequency conversion, while maintaining a highdamage threshold.Anticipated Results /Potential Commercial Applications as described by the awarder: New material and coating technologieswill be developed which could be utilized in frequency-agilelaser systems. Applications range from remote sensing ofatmospheric constituents, such as ozone, to studies of variouschemical processes which occur in the ultraviolet region of thespectrum.
