$diffraction grating film sheets$

$diffraction grating film sheets$

#DIFFRACTION GRATING FILM SHEETS HOW TO#

The proposed metasurface based on vanadium dioxide (VO 2) shows thermally controlled reconfigurability and incident direction dependence, thus manifesting four independent EM functionalities in the whole space. Here, we studied the directional THz holography using a proposed reconfigurable Janus metasurface.

#DIFFRACTION GRATING FILM SHEETS HOW TO#

However, how to realize direction-dependent and reconfigurable THz metasurface is still an untapped area. Recently, based on various tunable materials, reconfigurable and programmable metasurfaces have achieved the multiplexing of incident polarization, frequency and angle 18, 32, 33, 34, 35. Multifunctional THz devices capable of dynamically reconfiguring the function are essential for further enhancing the data storage capacity and expanding application scenarios. The manifold spectrum resources and the compactness of the system make THz wave promising in applications such as high-capacity data communication and high-security EM encryption 29, 30, 31. However, due to the difficulty in designing and fabricating the devices integrated with active components, EM functionalities of the Janus metasurface are always static, limiting their application prospects 22, 23, 24, 25, 26, 27, 28. Towards practical applications of direction-dependent metasurfaces, the reconfigurability with the change of external incentives is highly expected 17, 18, 19, 20, 21.

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Compared to conventional metasurface holography, the additional freedom brought by the propagation direction in Janus metasurface can further enhance the design space and information capacity. The Janus metasurface consisting of a stack of twisted meta-sheets can act as free-space holographic imagers for opposite propagation directions. Recently, asymmetric but still reciprocal transmission in opposite propagation directions using symmetry-broken structures has been reported 16, showing unconventional wavefront tailoring in a direction-determined manner. Although nonreciprocal devices could be created to realize direction-dependent manipulation of EM waves by breaking the time-reversal symmetries using magneto-optic materials 10, 11, nonlinear materials 12, 13, and time-variant materials 14, 15, the apparatus used for external control is always complicated and bulky. However, most existing multifunctional metasurfaces do not exploit this design freedom. The requirement of asymmetric wave manipulation widely exists in practical applications such as laser technologies 4, 5, antenna radomes 6, 7, full-duplex communication 8, 9, etc. The wave propagation direction is a vital wave property and its multiplexing endows the metasurface with rich functions in two asymmetric channels. With the development of compact and integrated systems, there are increasing demands on integrating multiple functionalities into a single metasurface. In the past decades, metasurfaces have drawn tremendous attention due to their unprecedented abilities to manipulate electromagnetic (EM) waves at will 1, 2, 3. This work not only offers a common strategy for realizing the reconfigurability of Janus metasurfaces, but also shows possible applications in THz optical information encryption, data storage, and smart windows. Such reconfigurable Janus metasurfaces can achieve asymmetric focusing of THz wave and directional THz holography with free-space image projections, and particularly the information can be manipulated via temperature and incident THz wave direction. Herein, we show that thermally activated THz Janus metasurfaces integrating with phase change materials on the meta-atoms can produce asymmetric transmission with the designed phase delays.

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Recently, it was demonstrated that Janus metasurfaces could produce distinct responses to EM waves from two opposite incident directions, making multiplexed dynamic manipulation of THz waves possible. Currently, an enormous challenge is to realize directional terahertz (THz) holography. Dynamic manipulation of electromagnetic (EM) waves with multiple degrees of freedom plays an essential role in enhancing information processing.

$diffraction grating film sheets$

Diffraction grating film sheets