Excitation mechanisms for upconversion lasers

Abstract

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:Er3+ and LaF3:Nd3+ whereas energy transfer upconversion dominated in YLiF4:Er3+. A nonlinear absorption process associated with cross relaxation resulted in upconversion lasing in YLiF4:Nd3+. © 1990.