Optical and polarization phase manipulation of diffraction from grating nanostructure at excited waveguide resonance

摘要

Resonant grating-waveguide structures can exhibit far field intensity spectra with narrow bandwidth around predefined wavelengths. In this paper we studied the spatial electromagnetic field distribution along with the Poynting vector distribution in the various layers of a resonant grating-waveguide structure, when it is subjected to polarization phase and polar and azimuth angle manipulation. It was found that there exists correlation of the confinement properties including the guided modes available and the evanescent field profile with the reflection and transmission efficiencies, as well as the polarization. A zero waveguide mode (TE_0 like) exists at (nearly) normal incidence. However, for incidence in conical mounting the confinement is similar to that of first waveguide mode (TE_1 like), and its confinement is not efficient which is correlated to the bandwidth. The refractive index of grating lines also essentially affects the resonance properties. Numerical dependence of the peak wavelength on the index is parabolic like.