On-chip excitation of single germanium vacancies in nanodiamonds embedded in plasmonic waveguides

摘要

Monolithic integration of quantum emitters in nanoscale plasmonic circuitry requires low-loss plasmonic configurations capable of confining light well below the diffraction limit.We demonstrated on-chip remote excitation of nanodiamond-embedded single quantum emitters by plasmonic modes of dielectric ridges atop colloidal silver crystals.The nanodiamonds were produced to incorporate single germanium-vacancy(GeV)centres,providing bright,spectrally narrow and stable single-photon sources suitable for highly integrated circuits.Using electron-beam lithography with hydrogen silsesquioxane(HSQ)resist,dielectric-loaded surface plasmon polariton waveguides(DLSPPWs)were fabricated on single crystalline silver plates to contain those of deposited nanodiamonds that are found to feature appropriate single GeV centres.The low-loss plasmonic configuration enabled the 532-nm pump laser light to propagate on-chip in the DLSPPW and reach to an embedded nanodiamond where a single GeV centre was incorporated.The remote GeV emitter was thereby excited and coupled to spatially confined DLSPPW modes with an outstanding figure-of-merit of 180 due to a~six-fold Purcell enhancement,~56%coupling efficiency and~33μm transmission length,thereby opening new avenues for the implementation of nanoscale functional quantum devices.