Dual-Band Planar Plasmonic Unidirectional Launching in a Semiannular Apertures Array

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• 作者：Shan Huang ; Chun-Yuan Wang ; Hung-Ying Chen ; Meng-Hsien Lin ; Yu-Jung Lu ; Shangjr Gwo
• 刊名：ACS Photonics
• 出版年：2016
• 出版时间：April 20, 2016
• 年：2016
• 卷：3
• 期：4
• 页码：584-589
• 全文大小：524K
• 年卷期：0
• ISSN：2330-4022

文摘

Multiple-band, frequency-adjustable unidirectional launching of planar surface plasmons is of great concern in plasmonic devices and circuits. We have designed and demonstrated a novel dual-band planar unidirectional surface plasmon polaritons (SPPs) launcher with narrow bandwidth (∼5 nm) and large band gap (∼50 nm) using a semiannular apertures array milled in a gold film. Symmetry breaking of the semiannular aperture brings significant advantages for the unidirectional launching, based on the excited asymmetrically distributed cylindrical surface plasmon resonance modes. During the unidirectional launching, the individual semiannular apertures function as unidirectional quasi-point SPP sources, and the grating coherently stacking amplitude of unidirectional SPPs functions as an amplifier. By controlling the semiannular aperture size, we achieved large range modulations of wavelengths beyond 60 nm for both bands. This efficient unidirectional launching is experimentally demonstrated for 632 nm, showing good agreement with numerical results.