Surface-plasmon–polariton excitation of optical microcavities and second-harmonic emission

Abstract

We have created microscopic Fabry–Perot optical resonator cavities between the flattened end of a tunneling microscope tip and a semitransparent metal film. Power is transferred to cavity modes from a laser beam by means of surface-plasmon–polariton generation and subsequent radiative decay. We compare the dependence of the axial emission from these modes on cavity length and on the angle of incidence with the predictions of a stratified-medium model. The mode structure has a finesse that approaches the theoretical limit. At high incident power, second-harmonic radiation produced by weakly localized surface-plasmon–polaritons is also coupled into the cavity and detected in axial emission.