Experimental investigation of 3D plasmon talbot effect

Three-dimensional (3D) plasmon Talbot effect is experimentally investigated on three finite-sized, two-dimensional (2D) periodical arrays composed of subwavelength nanoholes with different fill factors. By using water as the output medium, both the focusing behavior and the plasmon Talbot revivals are clearly observed even when the operating wavelength is larger than the array period. And theoretically, with the output material having a refractive index of n, the operating wavelength to realize the plasmon Talbot effect can be enlarged by a factor of n-1. The integral and fractional plasmon Talbot revivals reproduce the device pattern with rich subwavelength hotspots (0.56~0.72λ) in exactly the same array period, which shows a great prospect for the low-cost, large-scale micro- and nanolithography. The preliminary experimental results indicate that the fill factor doesn't play an obvious influence on the size of the achieved plasmon Talbot hotspots.