Transmission enhancement through square coaxial aperture arrays in metallic film: when leaky modes filter infrared light for multispectral imaging.

The diffractive behavior of arrays of square coaxial apertures in a gold layer is studied. These structures exhibit a resonant transmission enhancement that is used to design tunable bandpass filters for multispectral imaging in the 7-13 μm wavelength range. A modal analysis is used for this design and the study of their spectral features.

Adaptive Perfectly Matched Layer for Wood's anomalies in diffraction gratings.

We propose an Adaptive Perfectly Matched Layer (APML) to be used in diffraction grating modeling. With a properly tailored co-ordinate stretching depending both on the incident field and on grating parameters, the APML may efficiently absorb diffracted orders near grazing angles (the so-called Wood's anomalies). The new design is implemented in a finite element method (FEM) scheme and applied on a numerical example of a dielectric slit grating.