Influence of Refractive Index to Plasmonic Interferometric Imaging

Plasmonic interferometric imaging has been widely used for fast and label-free detection to nano-objects, which associates the interference between launched and scattered surface plasmon polaritons (SPPs). As scattering of SPPs is affected by the characteristics of nano-objects, particle size, particle index and particle-interface distances have been retrieved from the imaging. Refractive index of dielectric, which tailors the resonant wavelength of launched SPPs, is also a key issue to plasmonic interferometric imaging. Yet, the influence of refractive index to plasmonic interferometric imaging has not been investigated. In this work, we connected the dielectric refractive index to the interferometric image intensity distribution, and found that both fringe periodicities and intensity profiles along SPP wavefronts were tailored by the refractive index, which is illustrated by using glucose solutions with different concentrations. Our research illustrates the pattern change of plasmonic interferometric imaging induced by dielectric refractive index, which not only paves the way for the basic understanding on the plasmonic interferometric imaging, but also provides a new potential visual method for real-time refractive index sensing and monitoring, which will be applied to food safety and environment monitoring.