Cao Tun, Tian Long, Liang Huawei, Qin Kai-Rong
1Department of Biomedical Engineering, Dalian University of Technology, Dalian, China.
2Shenzhen Key Laboratory of Laser Engineering, College of Optoelectronic Engineering, Shenzhen University, Shenzhen, China.
Microsyst Nanoeng. 2018 May 21;4:7. doi: 10.1038/s41378-018-0008-3. eCollection 2018.
Chiral surface plasmon polaritons (SPPs) produced by plasmonic nanowires can be used to enhance molecular spectroscopy for biosensing applications. Nevertheless, the switchable stereoselectivity and detection of various analytes are limited by a lack of switchable, chiral SPPs. Using both finite-element method simulations and analytic calculations, we present a graphene-coated chalcogenide (GCC) nanowire that produces mid-infrared, chiral SPPs. The chiral SPPs can be reversibly switched between "on" (transparent) and "off" (opaque) by non-volatile structural state transitions in the dielectric constants of the chalcogenide glass Ge2Sb2Te5. Furthermore, by controlling the Fermi energy of the graphene-coating layer, the nanowire can output either non-chiral or chiral SPPs. A thermal-electric model was built to illustrate the possibility of ultrafast on/off switching of the SPPs at the terminus of the nanowire. Finally, we show that a selective, lateral sorting of sub-10-nm enantiomers can be achieved via the GCC nanowire. Chiral nanoparticles with opposite handedness experience transverse forces that differ in both their sign and magnitude. Our design may pave the way for plasmonic nanowire networks and tunable nanophotonic devices, which require the ultrafast switching of SPPs, and provide a possible approach for a compact, enantiopure synthesis.
由等离子体纳米线产生的手性表面等离激元极化激元（SPPs）可用于增强用于生物传感应用的分子光谱。然而，由于缺乏可切换的手性SPPs，各种分析物的可切换立体选择性和检测受到限制。通过有限元方法模拟和解析计算，我们展示了一种石墨烯包覆硫族化物（GCC）纳米线，它能产生中红外手性SPPs。手性SPPs可通过硫族化物玻璃Ge2Sb2Te5介电常数中的非挥发性结构状态转变在“开”（透明）和“关”（不透明）之间可逆切换。此外，通过控制石墨烯涂层的费米能量，纳米线可以输出非手性或手性SPPs。建立了一个热电模型来说明纳米线末端SPPs超快开/关切换的可能性。最后，我们表明通过GCC纳米线可以实现对亚10纳米对映体的选择性横向分选。具有相反手性的手性纳米颗粒所经历的横向力在符号和大小上都有所不同。我们的设计可能为需要SPPs超快切换的等离子体纳米线网络和可调谐纳米光子器件铺平道路，并为紧凑的对映体纯合成提供一种可能的方法。
