文摘
We experimentally demonstrate an enhanced refractive index sensing using a dislocated double-layered metal grating (DDMG). The DDMG is capable of supporting a novel guided mode caused by the interaction between localized surface plasmon resonances (LSPRs) from the individual gold stripes and Wood’s anomaly in the dielectric grating layer between two gold gratings. We show that this guided mode can only be induced and mediated by the coupling of lattice plasmon resonances sustained by upper and lower gold grating through introducing a lateral displacement between the two gold gratings. The DDMG provides an experimental figure of merit (FOM) value up to 36 under normal incidence, which is superior to those of most of nanoplasmonic sensors relying on Fano resonances. Additionally, the DDMGs can be fabricated by a very simple and cost-effective method via a combination of two-beam interference lithography and metal deposition. Accompanied with high FOM and simple detection scheme, this sensor will be found in a wide range of applications in biomedical sensing. Keywords Localized surface plasmon resonance Refractive index sensing Figure of merit Wood’s anomaly Fano resonance