title: Ultra-broadband and efficient surface plasmon polariton launching through metallic nanoslits of subwavelength period.
abstract: Ultra-broadband, efficient and unidirectional surface plasmon polariton (SPP) launching is of great concern in plasmonic devices and circuits. To address this challenge, a novel method adopting deep-subwavelength slits of subwavelength period (λSPP/4 ~ λSPP/3) in a thick metal film and under backside illumination is proposed. A new band pattern featuring broadband and wide angular characteristics, which is due to the coupling of the zeroth-order SPP resonance at the superstrate-metal interface and the first-order SPP resonance at the metal-substrate interface, is observed for the first time in the dispersion diagram. Unidirectional SPP launching efficiency of ~50%, ultra-broad bandwidth of up to 780 nm, covering the entire optical fiber communication bands, and relatively wide angular range of 7° are achieved. This remarkable efficient, ultra-broadband and wide angular performance is demonstrated by carefully designed experiments in the near infrared regime, showing good agreement with numerical results.
authors.affiliation: State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871, China.
authors.forename: Guangyuan
authors.initials: G
authors.lastname: Li
authors.affiliation: 1] State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871, China [2] Collaborative Innovation Center of Quantum Matter, Beijing 100871, China.
authors.forename: Jiasen
authors.initials: J
authors.lastname: Zhang
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