Exploring the negative diffraction order in plasmonic crystals by refractive index engineering

In this paper an engineered dielectric material is used to introduce porosities which will change the plasmonic crystal's (PCL) refractive index profile, its excitation conditions, electromagnetic (EM) characteristics and propagations. SPP excitation is moved from positive diffraction order (m=1) to negative diffraction order range (m=-1); hence the increment in wavelength will decrease the resonant angle. The m=-1 opens the possibility to control and manipulate the preferred excitation conditions of SPP for different purposes such as optical devices and sensors.