High-Efficiency All-Dielectric Huygens Metasurfaces from the Ultraviolet to the Infrared

Abstract

Conventional optics depend on the gradual accumulation of spatially dependent phase shifts imparted on light propagating through a medium to modify the wavefront of an incident beam. A similar effect may be obtained by the imposition of abrupt, discrete phase changes on a propagating wavefront over a subwavelength scale using photonic metasurfaces. Highly efficient metasurfaces have applications ranging from conventional optics to high-efficiency solar energy conversion, optical communications, and more. We present here the design, computational modeling, and experimental demonstration of all-dielectric transmissive Huygens metasurfaces exhibiting anomalous refraction, defined as the controlled deflection of light at an interface as a function of subwavelength nanostructures. These metasurfaces are composed of dielectric, cylindrical elements, characterized by balanced electric and magnetic dipole resonances. For infrared wavelengths, optical efficiency of 91.3% is demonstrated computationally, and experimental efficiency of 63.6% is measured. Metasurfaces are designed and modeled in each of three experimentally realizable material systems, corresponding to incident wavelengths in the ultraviolet, visible, and infrared, all demonstrating high optical efficiency of at least 78%. A ground-up approach is presented that enables this design of highly efficient all-dielectric Huygens metasurfaces with nonzero phase gradients, in spite of difficulties due to strong interantenna coupling effects. Additionally, we computationally demonstrate a stacked metasurface device, capable of independent manipulation of four adjacent spectral bands, with midband optical efficiency as high as 55%. Taking advantage of the high sensitivity of this resonant dielectric Huygens metasurface approach, we discuss routes to the development of optical sensors and dynamically tunable metasurfaces.

High-Efficiency, Broadband, Near Diffraction-Limited, Dielectric Metalens in Ultraviolet Spectrum

“…As mentioned above, earlier reported work on the metalenses in the UV range is lean and they do not operate in a broadband UV spectrum, and hence are defocused on a small UV range. Moreover, the focusing efficiency and the polarization conversion efficiency of the unit cell is not as high as reported in our work [38,45,46]. Our design of a 2-D, dielectric UV metalens is based on silicon nitride Si 3 N 4 metasurface, exhibiting high efficiency with a full phase delay of 2π for the broadband UV range (250-400 nm) using PB phase.…”

“…Previously reported work on metalenses has focused on various wavelengths ranging from ultraviolet to near-infrared [38], but these metalenses defocused at a small range of UV spectrum due to the insufficient phase delay. Phase manipulation can be realized by various methods depending on principles; for instance, Huygens metasurfaces [39,40], surface plasmon wave-guiding [41,42] and dielectric effective refracting [43,44].…”

Dielectric metasurfaces for distance measurements and three-dimensional imaging

“…Full 2π phase coverage has been achieved with several metasurface designs before by changing in-plane geometry parameters like the size of the nanoresonators or the period of their arrangement. 6,9,12,[45][46][47][48] Here, we consider polarization-independent Huygens' metasurfaces consisting of silicon nanodisks in a square lattice. The geometry is schematically shown in Fig.…”

Characterization of Dynamic and Nanoscale Materials and Metamaterials with Continuously Referenced Interferometry

“…A variety of techniques to achieve this have been demonstrated, using variable control of either geometric or intrinsic material parameters. The development of these technologies and devices can require or benefit from the measurement of transmitted or reflected phase . Interferometry offers a natural means to make this measurement, although there are several inherent challenges.…”