Spectroscopic Evaluation of Nd(3+): CAMGAR and Ho(3+):YLF as 0.94 micrometers Lasers.
MASSACHUSETTS INST OF TECH CAMBRIDGE
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An efficient laser operating near the o.94 micrometer wavelength is of interest because with frequency doubling one can have a 470 nm laser with potentially higher overall efficiency than any primary laser at this wavelength. Nd3 in most oxide garnet host crystals has a 0.94 micrometer transition. What is required for 0.94 micrometer transition and a large branching ratio of 0.94 micrometer emission relative to the 1.06 emission. Detailed spectroscopy was performed on NdCAMGAR in order to determine the relevant cross sections. The results show that the 1.06 micrometer cross section in CAMGAR is about 0.25 of the 1.06 micrometer cross section in YAG whereas the ratio of the 0.94 micrometer cross sections is 0.5. Laser experiments on both NdYAG and NdCAMGAR by longitudinal pumping with an Ar laser substantially verified the relative cross sections of the two materials, The 0.94 micrometers results were limited however and the resulting cross section for NdCAMGAR is higher than the spectroscopically determined value. HO3 is an alternate ion for a 0.94 micrometer laser. The Ho 5F5 level to 5I7 level has been reported lased at 0.98 epsilon micrometer both in 2 in LiYF4 and in LiHoF4. An analysis of HoYLF has been done to evaluate its potential as a useful laser material.
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