Huygens' principle is a well-known concept in electromagnetics that dates back to 1690. Here, it is applied to develop designer surfaces that provide extreme control of electromagnetic wave fronts across electrically thin layers. These reflectionless surfaces, referred to as metamaterial Huygens' surfaces, provide new beam shaping, steering, and focusing capabilities. The metamaterial Huygens' surfaces are realized with two-dimensional arrays of polarizable particles that provide both electric and magnetic polarization currents to generate prescribed wave fronts. A straightforward design methodology is demonstrated and applied to develop a beam-refracting surface and a Gaussian-to-Bessel beam transformer. Metamaterial Huygens' surfaces could find a wide range of applications over the entire electromagnetic spectrum including single-surface lenses, polarization controlling devices, stealth technologies, and perfect absorbers.

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Metamaterial Huygens' surfaces manipulate electromagnetic wavefronts without reflection. A broadband Huygens' surface that efficiently refracts normally incident light at the telecommunication wavelength of 1.5 μm is reported. The electric and magnetic responses of the surface are independently controlled by cascading three patterned, metallic sheets with a subwavelength overall thickness of 430 nm. The peak efficiency of the device is significantly enhanced by reducing the polarization and reflection losses that are inherent to earlier single-layer designs.

It is experimentally shown that bianisotropic metasurfaces allow for extreme polarization control of light with high performance. A metasurface providing asymmetric transmission (i.e., polarization conversion) of circularly polarized light is reported at a wavelength of 1.5  μm. The experimental transmittance and extinction ratio are 50% and 20:1, which represents an order of magnitude improvement over previous optical structures exhibiting asymmetric transmission. The metasurface consists of patterned gold sheets that are spaced at a subwavelength distance from each other. The same design and fabrication processes can be used in the future to completely control the phase, amplitude, and polarization of light.

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