Multi-reflection process of extraordinary optical transmission in a single subwavelength metal slit

摘要

The process of the light passing through a single subwavelength metal slit is analyzed by the finite-difference time-domain method. The simulation results show that the slit can be considered as an effective dielectric region sandwiched by two scattering regions at the two slit ends. Thus, the slit is analogous to a Fabry-Perot (FP) etalon consisting of a dielectric slab with high-reflection coatings on its two surfaces. A formula is presented to evaluate the phase shift caused by the amplitude transmissivity of the coatings.