Figure 1
APS/Carin Cain; Image on homepage: C. Pfeiffer and A. Grbic [1]

Figure 1: (a) Conventional optical lenses for focusing or defocusing a beam. These devices operate based on the accumulation of a phase delay and therefore are commonly much larger than the wavelength of operation. (b) Huygens metasurfaces can achieve similar effects by locally controlling electric (Je) and magnetic (Jm) currents induced on the surface. The effect is obtained over a subwavelength thickness, with no reflection and large transmission efficiency.