Berlin 2018 – wissenschaftliches Programm

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 5: Whispering Gallery Mode Resonators II

KFM 5.5: Vortrag

Montag, 12. März 2018, 16:50–17:10, EMH 025

Near infrared cathodoluminescence measurements on paraboloidal and conical silicon photonic nanoresonators — •Sebastian W. Schmitt, Klaus Schwarzburg, and Catherine Dubourdieu — Helmholtz-Zentrum Berlin für Materialien und Energie

Due to the indirect band-to-band transition, spontaneous emission rates in silicon (Si) are low and efficient Si-based solid state lighting remains challenging. The confinement of spectrally matched optical modes can amplify spontaneous emission rates of electronic transitions in Si nanophotonic resonators. Hereby, the amplification is proportional to Q/V, where Q is the quality factor and V is the volume of the resonant mode. This so-called Purcell effect could successfully be applied to improve the performance of Si-based light emitters. Here, Si acts as active or passive resonator material amplifying intrinsic band-to-band or defect transitions or the transitions of added gain media. We show cathodoluminecence (CL) measurements performed in a scanning electron microscope on two novel types of Si photonic resonators with inverted conical and inverted paraboloidal geometry. CL scanning of the resonators by the electron beam at different heights shows a selective excitation of optical whispering gallery modes in the near-infrared wavelength range. A discussion of the excited modes with respect to Q-factor, polarization, relative intensity and resonator geometry shows that the nanoresonators permit a strong and tunable light amplification in the telecom window and accordingly are suitable building blocks for small on-chip solid state lighting devices.