Polarization dependence of light intensity distribution from nanometer metallic slits

In this work, the near-field and far-field electric magnetic (EM) wave distributions of metallic slits was observed using tapered fiber probe and modelled using finite difference time domain (FDTD) computer simulations. The EM wave field distribution from rectangular slits with widths 100 nm, 300 nm, and 500 nm was mapped with excitation wavelength λ = 532 nm. λ/2 can be considered a characteristic length for the problem. From the experiments and FDTD simulation, E_⊥ wave is found to be governed by the surface plasmon wave (SPW) which results in ill near field pattern and cannot be confined in the slit. On the contrary, E_|| wave has a well-shaped field distribution and can be confined in the slit.