Stimulated emission at the approximate wavelengths of 840 nm, 1860 nm, 2050 nm, 2690 nm, and 2830 nm is obtained from birefrigent laser single crystals of calcium fluoride and the fluorides selected from the trivalent rare earth elements. Each crystal has a structure which deviates from the cubic lattice structure of calcium fluoride and tends toward the hexagonal lattice structure of the rare earth fluorides. The deivation in crystal structure is generally produced by increasing the percent by weight of the rare earth fluoride in excess of 3% and up to 50% of the crystalline solution. Examples of the fluorescent composition include CaF2:xErF3:yYbf3:zTmF3:wHoF3, where x varies from 3% to 50%, y varies from 0% to 3%, z varies from 0% to 3% and w varies from 0% to 3% (all percent by weight). Other rare earth ions, having absorption bands which overlap the output spectum of the pumping means over a wide region, may be used in place of erbium ions.
展开▼
