Full‐Color Complex‐Amplitude Vectorial Holograms Based on Multi‐Freedom Metasurfaces

Abstract

Phase, polarization, amplitude, and frequency represent the basic dimensions of light, playing crucial roles for both fundamental light-material interactions and all major optical applications. Metasurfaces have emerged as a compact platform to manipulate these knobs, but previous metasurfaces have limited flexibility to simultaneous control them. A multi-freedom metasurface that can simultaneously and independently modulate phase, polarization, and amplitude in an analytical form is introduced, and frequency multiplexing is further realized by a k-space engineering technique. The multi-freedom metasurface seamlessly combines geometric Pancharatnam-Berry phase and detour phase, both of which are frequency independent. As a result, it allows complex-amplitude vectorial hologram at various frequencies based on the same design strategy, without sophisticated nanostructure searching of massive geometric parameters. Based on this principle, full-color complexamplitude vectorial meta-holograms in the visible are experimentally demonstrated with a metal-insulator-metal architecture, unlocking the longsought full potential of advanced light field manipulation through ultrathin metasurfaces.functional layers, emerge as a desirable platform to manipulate the light field at will with large control and flexibility. [3][4][5][6][7] Exciting applications have already been demonstrated on the metasurface platform, including flat diffractive and polarization optical components, much more compact and lightweight than conventional bulky counterparts. By engineering the scattering properties of the individual metaelements constituting the metasurface to mold the geometric phase, resonant phase or propagation phase, we are able to control phase, [8,9] amplitude, [10,11] polarization, [12,13] or frequency [14][15][16] of light, leading to high-efficiency metalenses, [9] high-fidelity holograms, [8] broadband polarization components, [12,17] and highperformance biosensors. [15] However, these ultrathin components tend to focus on single-dimensional light manipulation, controlling either the local phase, or amplitude, or polarization, or frequency, at a time, inherently limiting potential opportunities. For example, metasurface holograms and metalenses based on resonant phase and propagation phase are typically limited to a narrow range of frequencies. [18,19] Geometric Pancharatnam-Berry (P-B) phase metasurfaces operate over broader bandwidths, but they are restricted to circular polarization only. [8] To improve the performance and enrich the functionality of metasurfaces for a broader range of applications, independent

Recent advances in multi-dimensional metasurfaces holographic technologies

“…b Design principle of the multi-freedom metasurfaces for completely controlling the amplitude, phase and polarization of output light simultaneously. The simulated and experimental results of reconstructed full-color images for different combinations of polarization orientations are shown on the bottom [29]. c Simulated and experimental results for the reconstruction of a dice with different exposed faces by using different combinations of input/output polarization [73].…”

“…With the development of nanofabrication technologies, metasurfaces consisting of arrays of plasmonic or dielectric nanoantennas have attracted enormous interest due to their ability to arbitrarily tailor the fundamental properties of the electromagnetic wavefront such as amplitude [10][11][12], phase [13][14][15][16][17], frequency [18,19], polarization [20][21][22] and orbital angular momentum (OAM) [23][24][25] within ultrashort distance. Meanwhile, simultaneously multiple parameters modulation methods have also been demonstrated [26][27][28][29][30], which make metasurface become a potential substitute for the traditional bulky optical elements. Metasurfaces have successfully achieved many novel applications of beam shaping [31][32][33][34], metalens [35][36][37][38][39], circular dichroism [40,41], nonlinear optics [42,43], color printing [44,45] and holography [46][47][48][49] .…”

A large field-of-view metasurface for complex-amplitude hologram breaking numerical aperture limitation

“…Similar defects also exist in amplitude-only holographic metasurfaces (AHM) [56][57][58][59][60][61]. Subsequently, with the emergence of the meta-atoms capable of simultaneously modulating the local phase and amplitude information, metasurfaces can be applied to perform the complex-amplitude holograms [35,45,[62][63][64][65][66][67]. Due to the additional degree of freedom in controlling the wave fronts, the complex-amplitude hologram metasurface (CAHM) is expected to exhibit superior imaging quality beyond PHM and AHM.…”

High-efficiency metadevices for bifunctional generations of vectorial optical fields

“…Designing metasurfaces to exhibit certain anisotropic or spatially inhomogeneous phase distributions for reflected/transmitted waves, researchers have demonstrated separate manipulations on polarization [10][11][12] or wave front [13][14][15][16][17][18] properties of EM waves, leading to many practical applications (e.g., polarization control [10][11][12], light-bender [13][14][15][16][17], metalens [19][20][21][22][23], and metahologram [24][25][26][27]). More recently, metadevices exhibiting combined functionalities of polarization and wave front manipulations were proposed [18,[28][29][30][31][32][33][34][35][36][37][38][39], some of which could already generate particular VOFs as desired [29][30][31][37][38][39][40]…”