Angle- and polarization-dependent spectral characteristics of circular grating filters

We design and implement one type of guided mode resonance (GMR) circular grating filters (CGFs) on an HfO2-on-silicon platform. Taking advantage of an angle-resolved micro-reflection measurement system, we achieve their incident angle- and polarization-dependent reflection spectra. For normal incident arbitrary linear polarization, a pair of reflection peaks is experimentally observed due to the coexistence of the azimuthal component E-a and the radial component E-r of the incident wave electric field (E-field). For oblique incident s-polarization (E-field perpendicular to the incident plane), the peak excited by the E-a component splits into two sub-peaks due to the removal of degeneracy, while that excited by the E-r component gradually fades away with the increase of the incident angle. For oblique incident p-polarization (E-field parallel to the incident plane), the spectrum appears to be reversed; that is, the peak corresponding to the E-r component gets split while that corresponding to the E-a component gradually disappears when the incident angle increases. Moreover, we experimentally demonstrate the spectral relationships between CGFs and linear grating filters under not only normal incidence but also oblique incidence; these relationships greatly facilitate the spectral design and tailoring of the CGFs. (C) 2016 Optical Society of America