Non-Periodic Symmetric Metallic Waveguide Arrays for Near-Field Focusing

We have performed finite-difference time-domain (FDTD) analysis of optical transmission through a two-dimensional non-periodic metallic planar waveguide array structure. Waveguide array is designed such that each waveguide transmits surface plasmons polaritions (SPPs) with phase retardation controlled by variable thickness of the gap. The calculation results show that the waveguide array focusing light beam as dielectric lens at subwavelength in near field, and potential in miniaturized photonic circuits, biosensing, and nanoimaging, etc.