In the work we demonstrate the formation of new type of polariton on the
interface between a cuprous oxide slab and a polystyrene micro-sphere placed on
the slab. The evanescent field of the resonant whispering gallery mode (WGM)
has a substantial gradient, and therefore effectively couples with the
quadrupole 1S excitons in cuprous oxide. This evanescent polariton has a long
life-time (1.7ns), which is determined only by its excitonic component. The
polariton lower branch has a well pronounced minimum. This suggests that this
excitation can be utilized for BEC. The spatial coherence of the polariton can
be improved by assembling the micro-spheres in a linear chain.Comment: 4 pages, 3 figures; APS/PREPRIN