Investigation of beaming light through nanoapertures using real metals for aperture based imaging devices

We investigated light beaming through nanoapertures surrounded by periodic corrugations as a technology for aperture based imaging. Using the Finite-Difference Time-Domain (FDTD) method, we performed simulations of nanoapertures in Perfect Electric Conductor (PEC), gold, and silver to predict the beam profile when varying the geometric parameters of the corrugations. We found that the results of the FDTD simulations for nanoapertures in PEC resembled those from the perfect conductor model presented in the literature, but the FDTD simulations using silver and gold did not predict beam formation. We fabricated nanoapertures surrounded by corrugations in silver films, and measured the beam profiles with knife-edge experiments. The measured beam profiles were narrower than predicted by the FDTD simulations, and there was no appreciable difference observed in the light transmitted through a nanoaperture with or without corrugations. The results suggest PEC is a poor approximation for real metals in surface plasmon assisted beaming applications.