Abstract: An imaging device comprises an input region that receives an input signal encoded in an envelope of an electromagnetic wave; a unit cell comprising at least one layer that is patterned to perform a spatio-temporal operation on the input signal; and an output region that generates an expected output signal that corresponds to a space-time derivative of the input signal.

Abstract: An optical combiner includes a first layer with a periodic arrangement of structures of a material with a first refractive index. A second layer overlies the structures on the first layer, and the second layer includes a material with a second refractive index. A difference between the first refractive index and the second refractive index, measured at 587.5 nm, is less than 1.5. The periodic arrangement of structures is configured such that the optical combiner produces, for an input signal incident on the first layer from air at an oblique elevation angle of greater than 20°, an output signal with three reflection peaks, each reflection peak having an average reflection of greater than 50% within a ±3° range of the elevation angle.

Abstract: An optical combiner includes a first layer with a periodic two-dimensional arrangement of structures arranged to support resonance for an input signal of a target wavelength, wherein the structures have a first refractive index. A second layer overlies the structures on the first layer, wherein the second layer includes a second material with a second refractive index, and wherein a difference between the first refractive index and the second refractive index, measured at 587.5 nm, is less than about 1.5. The periodic arrangement of structures is configured such that the optical combiner produces, for the input signal incident on the first layer from air at an oblique elevation angle of greater than about 20°, an output signal with a reflection peak with an average reflection of greater than about 50% within a ± 5° range of the elevation angle.