Metasurface Modeling of Periodic Diffraction Gratings based on Generalized Sheet Transition Conditions (GSTCs)

Space-modulated diffraction gratings are modelled and analyzed using a zero thickness metasurface grating approach, and demonstrated using numerical examples. The constitutive parameters of the grating are described using surface susceptibilities of the Lorentzian form, where their resonant frequencies are sinusoidally modulated. They are then solved self-consistently with the Generalized Sheet Transition Conditions (GSTCs) to determine the scattered fields from the metasurface for specified plane-wave incident fields, for various cases of modulation periodicities and depths.