Influence of whispering gallery modes (WGMs) on energy transfer

► Förster resonance energy transfer (FRET) studied in single microcavities. ► Overlap integral is larger in the smaller microcavity than in the bulk. ► Efficiency of the FRET is enhanced by a factor of 2 in smaller microcavity. ► FRET rate is thousand times larger in single microcavities.