Design of mechanically robust metasurface lenses for RGB colors

Abstract

In recent years, dielectric rod based metasurface lenses have been particularly investigated for their potential applications in replacing the traditional bulky lens with high efficiency. However, the isolated granular structure may lead to robustness and chromatic aberration concerns. In this work, a low refractive-index embedding medium was applied to solve the structural stability problem that also enables the device to be transferable to desired position or surface. Based on this, a compound metasurface lens composed of randomly interleaved frequency-selective zone sectors is proposed to broaden the bandwidth of the two-dimensional device. The validities of the proposed method and the application potentials for the multifunctional lens that can manipulate RGB three colors have been numerically examined and verified. The current results are of essence in guiding the future design of metasurface lenses for real practice.Metasurface as initially introduced to generalize the Snell's law, which is actually a special case of the grating equation, has attracted great research interests in the field of metamaterials. It enables the manipulation of electromagnetic wave propagation with a gradient geometrical phase profile [1][2][3][4][5][6] . The two-dimensional artificial structure composed of arrays of subwavelength scatters could produce anomalous reflection and refraction phenomena 7,8 , which is practically more promising in realization compared with the three-dimensional ones. the metasurface lens is mostly investigated with the expectation to replace the traditional bulky lens by a piece of structured surface layer, which may hopefully bring about significant advancements for modern optical systems [26][27][28][29][30][31][32] . Compared with the existing thin film based Fresnel's lens that is mainly to yield a required phase profile, the metasurface lens can deal with both transmission magnitude and phase and even polarization in subwavelength scale resolutions. The increased freedoms

Analog Optical Spatial Differentiators Based on Dielectric Metasurfaces

“…Optical Mater. 2020, 8,1901523 www.advopticalmat.de the same setup (see Figure 4d,e). The reflected intensity image clearly manifests the outline of the letters.…”

“…Optical Mater. 2020, 8,1901523 www.advopticalmat.de the metasurface. The output field intensity patterns of the ideal device (the ideal transfer function H(θ) is given in Equation (2) with β = 42, the blue solid line) and the actual device (H(θ) is shown in Figure 1d, the blue dashed line) when the input field pattern at the metasurface interface is U 0 (x′) = exp[−(x′/w) 2 ] (w = 80λ) at θ 0 = 25.4° (black line) are given in Figure 2b.…”

“…Optical Mater. 2020, 8,1901523 indexes of the silicon and gold were interpolated values according to the work. [34] A TM-polarized incident plane-wave was used as the excitation.…”

“…Metamaterials composed of artificial subwavelength structures have exhibited flexible modulation on phase, amplitude, and polarization of electromagnetic waves Metasurfaces, usually regarded as the 2D version of metamaterials, are also of the strong capabilities to manipulate waves and have already generated a great number of promising optical functionalities such as imaging, holography, spectroscopy, and even quantum entanglement . Its monolithic design will afford the special convenience to build optical computational devices.…”

Multifunctional Metasurface: Coplanar Embedded Design for Metalens and Nanoprinted Display

“…In this context, Wen et al demonstrated a spherical-to-cylindrical variable lens or a lens-to-hologram variable device dependent on the helicity of the incident light. , In 2017, Mueller et al presented a method that can independently control the phase profile of orthogonal polarizations and experimentally demonstrated a circular polarization hologram and an elliptical polarization beam splitter in the visible . Microwave multifunctional metasurfaces with transmission and reflection EM response functions have been proposed by tailoring orthogonal polarizations. − Besides this polarization multiplexing, the spatial multiplexing also enables versatile functionalities, such as controlling the dispersion properties of metasurfaces , and realizing a passive Janus metasurface that has two different functions for opposite incident directions . Furthermore, dynamical tuning, such as using microfluidic channels, , phase-change materials, − elastic materials, , and electric resistor, has also been investigated to achieve multifunctional properties based on metasurfaces.…”