We theoretically investigate the optical transmission through a subwavelength slit covered with a nanostrip and
surrounded by corrugations in a metal film. Simulations results show that with a nanostrip on top of the slit, the optical
transmission efficiency through the slit surrounded by grooves is greatly enhanced for various angles of incidence
compared with the structure without the nanostrip. The nanostrip should be thick enough to result in an air nanocavity
with high Q value and enhanced transmission efficiency.
We proposed a compact surface wave polarization splitter based on the metallic-dielectric-air (MDA) waveguide with an
slit surrounded by asymmetric corrugations. The incident light coupled to the MDA waveguide through the aperture is
split into TE- and TM-polarized electromagnetic surface modes by the polarization-sensitive corrugations on each side.
Polarization extinction ratios better than 20 dB are achieved for both polarizations. The structure would be interesting for
a variety of optical devices and nanophotonics.
A novel optical coupler to access free-space optical signals in subwavelength scale into dielectric waveguide via a
plasmonic concentrator and a dielectric microring with field enhancement is proposed. The coupler is useful as it
combines the plasmonic concentrator, which is used to access optical signals in subwavelength scale, a microring
resonator for the coupling, with the dielectric waveguide for long distance optical transmission and processing.
The interactions between the optical light and sub-wavelength structures in metal film have sparked great interest on surface plasmon polaritons (SPPs). One effective way to interpret these phenomena is to make use of the phase shift between the SPP excited and the incident wave. Many theoretical and experimental studies have shown that this shift approximate to π is intrinsic at normal incidence. In this paper, the phase shift at oblique incidence is analyzed and used to interpret the transmission effect for the first time to our knowledge. A simplified 2D scattering formulation using vector finite element method is set up. Simulations show the phase shift can be approximate to π over a large range of incidence angles. With this shift, the conditions for the enhanced or suppressed transmission and the corresponding destructive or constructive interference of SPPs at oblique incidence are achieved. The transmission effect for incidence angle not satisfying these conditions, as well as its potential applications is also discussed.
A 16- and a 32-element irregular optical phased array based on silicon-on-insulator materials were fabricated. Such a device consists of an array of irregularly spaced single-mode waveguides, each of which has a specific length to give an appropriate phase retardation controllable by the wavelength. The optical beam can be steered continuously in the range of about 0 to 3 deg, corresponding to the wavelength varying from 1550.7 to 1551.9 nm.