The pumping intensity and concentration dependences of the fluorescence output from three infrared quantumhyphen;counter schemes that involve coupled ions in Er3plus;hyphen;doped SrF2have been measured at 300 and 77deg;K. The pumping intensity depended linearly on the numbers of photons absorbed in the schemes. The power of the concentration dependence was found to be noninteger in the range 1percnt;ndash;10percnt;. This has been interpreted as indicating the importance of energy migration between the Er3plus;ions as mechanism for populating the energy levels of the coupled ions.
展开▼
