2 × 1D crossed strongly modulated gratings for polarization independent tunable narrowband transmission filters.

We design a narrowband polarization independent transmission guided mode resonance filter whose center wavelength is tunable with respect to the angle of incidence. The device is composed of two identical structures assembled back to back. Each half structure is a dielectric multilayer stack in which a grating is engraved.

Experimental demonstration of 1D crossed gratings for polarization-independent high-Q filtering.

We demonstrate experimentally a spectral filter with high Q-factor (≃3238), wide accordability range (1500-1600 nm) with respect to the angle of incidence, and record polarization independence. This work is an experimental validation of the theoretical work reported in [Opt. Lett.

Tunable, polarization independent, narrow-band filtering with one-dimensional crossed resonant gratings.

We propose an optical component for widely tunable, narrow-band filtering. It takes advantage of the tunability properties, with respect to the angle of incidence, of guided-mode resonance filters. The intrinsic polarization sensitivity of the resonances is suppressed by exciting the modes through two identical, differently oriented one-dimensional gratings flanking a thick substrate.

Measurement and modeling of 2D hexagonal resonant-grating filter performance.

We report the measurement of a polarization-independent guided-mode resonant filter with a Q factor of approximately 2200 functioning near normal incidence in the near infrared (850 nm). Besides this remarkable performance, we provide a detailed optical and structural characterization of the component, which points out the origins of the limitation of the experimental performance. We conclude that the defaults in question can be corrected by improving the lithography process, and we are confident that even greater performance will be obtained in future realizations.

Experimental characterization of subwavelength diffraction gratings by an inverse-scattering neural method.

Characterization of gratings with small period-to-wavelength ratios is difficult to perform but is very helpful in improving the fabrication process. We experimentally tested an inverse-scattering method using a neural network on silicon etched gratings. We also characterized the gratings by using two popular microscopic methods.