Surface phonon polaritons(SPhPs)exhibit promising advantages(e.g.,low loss,long lifetimes)for mid/far-infrared(MIR/FIR)nanophotonics.However,FIR SPhPs experiments remain challenging for conventional optics and scatter...Surface phonon polaritons(SPhPs)exhibit promising advantages(e.g.,low loss,long lifetimes)for mid/far-infrared(MIR/FIR)nanophotonics.However,FIR SPhPs experiments remain challenging for conventional optics and scatteringtype scanning near-field optical microscopy(s-SNOM)due to the lack of compatible light sources/detectors.In this work,we characterized~75-110 meV SPhPs in AlN nanowires using a monochromated scanning transmission electron microscope(STEM)equipped with electron energy loss spectroscopy(EELS).This technique provided exceptional 4.3 meV energy resolution and sub-angstrom spatial resolution.We observed the evolution of SPhP interference fringes with propagation distance,derived the dispersion curve,and clarified size effects on SPhP propagation by tuning AlN structure dimensions.Experimental-numerical cross-validation confirmed that the local continuum model(LCM)accurately describes AlN's SPhP behaviors.This work advances the understanding of FIR SPhPs in polar dielectrics and establishes a robust platform for studying FIR phonon polariton materials.展开更多
基金supported by the National Key R&D Program of China(Grant No.2023YFB3609903)the National Natural Science Foundation of China(Grant Nos.52125307and 12404192)+1 种基金the“2011 Program”from the Peking–Tsinghua–IOP Collaborative Innovation Center of Quantum Mattersupport from the New Cornerstone Science Foundation through the XPLORER PRIZE。
文摘Surface phonon polaritons(SPhPs)exhibit promising advantages(e.g.,low loss,long lifetimes)for mid/far-infrared(MIR/FIR)nanophotonics.However,FIR SPhPs experiments remain challenging for conventional optics and scatteringtype scanning near-field optical microscopy(s-SNOM)due to the lack of compatible light sources/detectors.In this work,we characterized~75-110 meV SPhPs in AlN nanowires using a monochromated scanning transmission electron microscope(STEM)equipped with electron energy loss spectroscopy(EELS).This technique provided exceptional 4.3 meV energy resolution and sub-angstrom spatial resolution.We observed the evolution of SPhP interference fringes with propagation distance,derived the dispersion curve,and clarified size effects on SPhP propagation by tuning AlN structure dimensions.Experimental-numerical cross-validation confirmed that the local continuum model(LCM)accurately describes AlN's SPhP behaviors.This work advances the understanding of FIR SPhPs in polar dielectrics and establishes a robust platform for studying FIR phonon polariton materials.
