We report on fractal-featured square and ring-shaped apertures with a Sierpinski carpet pattern(SCP)on metallic and superconducting NbN films.Multiple extraordinary terahertz(THz)transmission peaks are studied in the ...We report on fractal-featured square and ring-shaped apertures with a Sierpinski carpet pattern(SCP)on metallic and superconducting NbN films.Multiple extraordinary terahertz(THz)transmission peaks are studied in the transmission spectra using both THz time-domain spectroscopy and numerical simulation.The characteristic transmission peaks are found to be associated with the interaction of surface plasmon polaritons(SPPs)and localized surface plasmons(LSPs)for ring-shaped apertures.The effect of LSPs is less remarkable in the square apertures.For the superconducting NbN film,when the temperature is slightly lower than the critical transition temperature T_(c),the peak magnitude of SPP resonances is most prominent due to the non-monotonic temperature dependence of kinetic inductance.These results provide a new way to design compact and efficient THz devices.展开更多
基金Supported by the National Basic Research Program of China(Nos 2011CBA00107,2011CBA00202)the National Natural Science Foundation of China under Grant Nos 61071009,61027008,11104110+1 种基金the Specialized Research Fund for Doctoral Program of Higher Education(20090091110040)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)。
文摘We report on fractal-featured square and ring-shaped apertures with a Sierpinski carpet pattern(SCP)on metallic and superconducting NbN films.Multiple extraordinary terahertz(THz)transmission peaks are studied in the transmission spectra using both THz time-domain spectroscopy and numerical simulation.The characteristic transmission peaks are found to be associated with the interaction of surface plasmon polaritons(SPPs)and localized surface plasmons(LSPs)for ring-shaped apertures.The effect of LSPs is less remarkable in the square apertures.For the superconducting NbN film,when the temperature is slightly lower than the critical transition temperature T_(c),the peak magnitude of SPP resonances is most prominent due to the non-monotonic temperature dependence of kinetic inductance.These results provide a new way to design compact and efficient THz devices.
