Interfacial refractive index sensing using visible-excited intrinsic zinc oxide photoluminescence coupled to whispering gallery modes

摘要

Whispering gallery modes (WGMs) excited by the intrinsic photoluminescence (PL) in zinc oxide microspherical resonators are investigated in this work. The microspheres were synthesized via a one-pot hydrothermal technique. A polymer was applied after the synthesis to fill remaining pores in the oxide particle. Defect-related ZnO PL was excited in the visible, coupling to WGMs. The observed WGMs red-shift with increasing refractive index of the surrounding medium with a sensitivity of 90-100 nm/refractive index unit. The spherical microresonators may be used to investigate binding to and structure at the particle/solution interface.