Dark mode metasurfaces: sensing optical phase difference with subradiant modes and Fano resonances

We computationally investigate the excitation of subradiant modes and Fano resonances of arrays of simple antenna elements with subwavelength dimensions. We show that periodic arrangements of dipoles on a flat surface provide a highly flexible approach for developing a range of metasurfaces with high sensitivity to both the wavelength of the incident radiation and angle of incidence. This provides a platform for the development of a range of metasurfaces with a wavelength-tunable sensitivity to phase gradients in an incident field.