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We report on an all-optical investigation of coupled spin excitation modes in a series of magnetic trilayer structures. Using time-resolved magneto-optic Kerr effect (tr-MOKE) magnetometry, we observe multi-mode coherent spin excitations in [Formula: see text]/Ru/[Formula: see text] multilayers even though the tr-MOKE optical detection is sensitive only to the [Formula: see text] magnetization dynamics. Frequency shifts of the different modes indicate that the coupling between the [Formula: see text] and [Formula: see text] layers varies from anti-ferromagnetic to ferromagnetic to uncoupled as the Ru spacer layer thickness is increased from 8 Å to 200 Å. The lifetime of the high frequency coherent oscillations in the [Formula: see text] layer increases by over 200%–300% even in the case of uncoupled [Formula: see text] and [Formula: see text] layers with a 200 Å thick Ru spacer. The results suggest an additional method to decrease the damping of high-moment alloys in layered magnetic nanostructures.