Direct upper-state pumping of the 2.8 mu m, Er/sup 3+/:YLF laser

Abstract

Direct resonant pumping of the /sup 4/I/sub 11/2/ upper state of the 2.8- mu m Er/sup 3+/:YLF laser at 0.97 mu m is shown to be more efficient than other pumping schemes which have been used for this transition. Upper-state pumping avoids nonradiative losses arising from phonon and self-quenching decays inherent in other pumping schemes. Efficient performance of the 2.8- mu m laser is maintained on condition that extremely shallow pump absorption is avoided. Reduced efficiency for shallow pump absorption is attributed to upconversion loss arising from high pumping rates.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>