K.A. Chao
Physical Review B
A number of nonlinear upconversion excitation mechanisms have been used to achieve lasing at wavelengths that are shorter than those of the pump light. We found that sequential two-step absorption was the principal process in YAlO3+ and LaF3+ whereas energy transfer upconversion dominated in YLiF4+. A nonlinear absorption process associated with cross relaxation resulted in upconversion lasing in YLiF4+. © 1990.
K.A. Chao
Physical Review B
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