Metal–dielectric biatomic structure for angulartolerant spectral filtering
We theoretically study metal–dielectric structures made of biatomic metallic gratings coupled to a guidedmode dielectric resonator. The biatomic pattern grating allows tailoring of the Fourier spectrum of the inverse grating permittivity in order to adapt the frequency gap and obtain a flat dispersion band over a wide angular range. A significant enhancement (twofold) of the angular tolerance as compared to a simply periodic structure is obtained.

a) Simply Periodic metallic Grating (SPG) filter. (b) Normal incidence transmission of filters with SPG on both sides (dark) and on one side (green). (c) Biatomic metallic gratingbased filter. (d) Dispersion relation for (blue) unperturbed and (red) perturbed guidemode 


Calculated angleresolved transmission diagrams as a function of the wavenumber σ and of the incident wavevector for two biatomic structures; d=3 μm, td=700 nm, tm=100 nm. (a) a=200 nm and l=500 nm. (b) a=300 nm and l=600 nm. 


Transmission at λR=4.02 μm as a function of the incidence angle for one SPG structure and one biatomic structure. Transmission spectra at different incidence angle for (b) the SPG structure and for (c) the biatomic structure. 

Contact: JeanLuc Pelouard
Further Reading: E. Sakat et al. Opt. Lett 38, 425 (2013).