Diffracted Beams from Metasurfaces: High Chiral Detectivity by Photothermal Deflection Technique

Measurements of difference in optical interactions between circularly polarized excitations opposite handedness (circular dichroism) are highly important for both natural and artificial chiral structures. Here the photothermal deflection technique is proposed as a method to detect chirality metasurface, analyzing diffracted beams by metasurface itself. Two metasurfaces investigated, based on Au Ag. The samples fabricated nanosphere lithography, with tilted deposition thin metal layer, which produces symmetry-breaking. unit cell periodicity these allows multiple order diffraction 450–520 nm range, encompasses emission lines an Ar laser. placed mirror excited pump beam at different orientations, laser wavelengths, circular polarization degree; probe scans absorption orders back-reflected from underlying mirror. In this way, investigation simplified placing scanning absorption-induced thermal effect into plane, thus avoiding transmission/reflection measurements specific order, done angular placement detector. Theoretical numerical approaches further developed reconstruct behavior nanoscale.