Ee Ho-Seok, Park Hong-Gyu, Kim Sun-Kyung
Appl Opt. 2016 Feb 10;55(5):1029-33. doi: 10.1364/AO.55.001029.
The surface plasmon polariton modes often excited in metallic nanocavities enable the miniaturization of photonic devices, even beyond the diffraction limit, yet their severe optical losses deteriorate device performance. This study proposes a design of metallic nanorod cavities coupled to plasmonic crystals with the aim of reducing the radiation loss of surface plasmon modes. Periodic Ag disks placed on an insulator-metal substrate open a substantial amount of plasmonic bandgaps (e.g., Δλ=290 nm at λ=1550 nm) by modifying their diameter and thickness. When an Ag nanorod with a length of ∼400 nm is surrounded by the periodic Ag disks, its Q-factor increases up to 127, yielding a 16-fold enhancement compared with a bare Ag nanorod, while its mode volume can be as small as 0.03(λ/2n)³. Ag nanorods with gradually increasing lengths exhibit high Q-factor plasmonic modes that are tunable within the plasmonic bandgap. These numerical studies on low-radiation-loss plasmonic modes excited in metallic nanocavities will promote the development of ultrasmall plasmonic devices.
金属纳米腔中经常激发的表面等离激元极化激元模式能够实现光子器件的小型化，甚至超越衍射极限，然而其严重的光学损耗会降低器件性能。本研究提出了一种将金属纳米棒腔与等离激元晶体耦合的设计，旨在降低表面等离激元模式的辐射损耗。放置在绝缘体 - 金属衬底上的周期性银盘通过改变其直径和厚度，打开了大量的等离激元带隙（例如，在波长λ = 1550 nm时，Δλ = 290 nm）。当一根长度约为400 nm的银纳米棒被周期性银盘包围时，其品质因数增加到127，与裸银纳米棒相比提高了16倍，而其模式体积可小至0.03(λ/2n)³。长度逐渐增加的银纳米棒展现出在等离激元带隙内可调谐的高品质因数等离激元模式。这些关于在金属纳米腔中激发的低辐射损耗等离激元模式的数值研究将推动超小等离激元器件的发展。
