Theoretical study of surface plasmons coupling in transition metallic alloy 2D binary grating

The excitation of a surface plasmon polariton (SPP) wave on a metal-air interface by a 2D diffraction grating is numerically investigated. The grating consists of homogeneous alloys of two metals of a formula A(x)B(1-x), or three metals of a formula A(x)B(y)C(z), where A, B and C could be silver (Ag), copper (Cu), gold (Au) or aluminum (Al). It is observed that all the alloys of two metals present a very small change of surface plasmon resonance (SPR) irrespective of composition x. Moreover, the addition of 25% of Al to two metals alloy is insufficient to change the SPR curves. The influence of the different grating parameters is discussed in details using rigorous coupled-wave analysis (RCWA) method. Furthermore, the SPR is highly dependent on grating periods (d(x) and d(y)) and the height of the grating h. The results reveal that d(x) = d(y) = 700 nm, h=40 nm and duty cycle w=0.5 are the optimal parameters for exciting SPP. (C) 2015 Elsevier B.V. All rights reserved.