Reversible Image Contrast Manipulation with Thermally Tunable Dielectric Metasurfaces

Abstract

Increasing demand for higher resolution of miniaturized displays requires techniques achieving high contrast tunability of the images. Employing metasurfaces for image contrast manipulation is a new and rapidly growing field of research aiming to address this need. Here, a new technique to achieve image tuning in a reversible fashion is demonstrated by dielectric metasurfaces composed of subwavelength resonators. It is demonstrated that by controlling the temperature of a metasurface the encoded transmission pattern can be tuned. To this end, two sets of nanoresonators composed of nonconcentric silicon disks with a hole that exhibit spectrally sharp Fano resonances and forming a Yin‐Yang pattern are designed and fabricated. Through exploitation of the thermo‐optical properties of silicon, full control of the contrast of the Yin‐Yang image is demonstrated by altering the metasurface temperature by ΔT ≈ 100 °C. This is the first demonstrated technique to control an image contrast by temperature. Importantly, the turning technique does not require manipulating the external stimulus, such as polarization or angle of the illumination and/or the refractive index of this environment. These results open many opportunities for transparent displays, optical switches, and tunable illumination systems.

Reversible switching of electromagnetically induced transparency in phase change metasurfaces

“…The NIR region is, however, a technologically important frequency regime with highly prominent applications, such as optical telecommunications and molecular sensing. [23][24][25][26][27] Recently, there have been some remarkable research efforts on the demonstration of actively tunable metasurfaces based upon a variety of functional materials, including chalcogenide glass phase change materials (PCMs), 28 liquid crystals (LCs), 29,30 epsilon-near-zero (ENZ) materials, 31,32 silicon, 33,34 and vanadium dioxide (VO 2 ). [35][36][37][38] Particularly, chalcogenide PCMs have attracted increasing attention due to their phase changing properties.…”

Giant photothermal nonlinearity in a single silicon nanostructure

“…In addition to the above applications, recently, there has been an emerging trend using thermo-optic effect to modulate metamaterial optical properties, such as polarization 37 , miniaturized image contrast 38 , and metalens focal length 39 . We envision that our result manifests the potential of pushing these various modulations toward all-optical control.…”

Anapole mediated giant photothermal nonlinearity in nanostructured silicon

“…3e. The large resonance tuning represents a significant improvement compared with previous studies using liquid crystals or thermo-optic effects [43][44][45][46] .We also remark here that free-carrier contributions are ruled out by the fact that they lead to a negative Δn, which causes the blue shift of the resonance 47 .…”