Optical metamirror: all-dielectric frequency-selective mirror with fully controllable reflection phase

Light control in conventional optical components relies on gradual phase changes along the light path. New artificial composites, so-called metasurfaces, offer possibilities for abrupt phase variations over the subwavelength scale. These functionalities pave the way for fundamentally new phenomena, such as anomalous refraction and reflection. Whereas full manipulation of refracted light can be attained with translucent dielectric Huygens’ composites, known means of full control of reflected beams still require reflector-backed structures which block light propagation at all spectrum. In this work, we demonstrate the first design of an all-dielectric frequency-selective mirror, a so-called metamirror, which provides desired high-efficiency manipulation of reflected light (in our example, realizing a focusing reflector) at the telecommunication wavelength of 1.5 μm, being practically transparent at other frequencies. The results can lead to a variety of new devices for telecommunications, integrated and nano-optics, and light energy harvesting.