Gain measurement and upconversion analysis in Tm/sup 3+/, Ho/sup 3+/ co-doped alumino-zirco-fluoride glass

The small signal gain coefficients were measured in Tm/sup 3+/,Ho/sup 3+/ co-doped alumino-zirco-fluoride glass. A gain of 15%/cm at 2.05 /spl mu/m was obtained for pump power density of 42 kW/cm/sup 2/. The temperature increase of the glass was found to be more than 150 K with this pump power, which was estimated from a comparison between fluorescence intensities of Tm/sup 3+/ /sup 3/F/sub 4/-/sup 3/H/sub 6/ and Ho/sup 3+/ /sup 5/I/sub 7/-/sup 5/I/sub 8/. An upconversion rate constant of 12.5/spl times/10/sup -17/ cm/sup 3/ sec/sup -1/ from a coupled (Tm/sup 3+/ /sup 3/F/sub 4/, Ho/sup 3+/ /sup 5/I/sub 7/) level to a coupled (Tm/sup 3+/ /sup 3/H/sub 5/, Ho/sup 3+/ /sup 5/I/sub 6/) level was determined by fitting the experimentally obtained gain coefficients to the calculated one which takes into consideration any temperature increase.<
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