Multiphysics simulations of adaptive metasurfaces at the meta-atom length scale

Meyer, Sebastian; Tan, Zhi Yang; Chigrin, Dmitry N.

doi:10.1515/nanoph-2019-0458

Cited by 16 publications

(15 citation statements)

References 51 publications

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“…4a). The existence and importance of this crystallization depth d for resonance tuning of GST-covered nanoantennas by optical switching has been demonstrated just recently 55,68 . Due to different thermal properties of the layers above and below the aIST layer, a temperature gradient arises from top to bottom.…”

Section: Resultsmentioning

confidence: 97%

In3SbTe2 as a programmable nanophotonics material platform for the infrared

et al. 2021

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The high dielectric optical contrast between the amorphous and crystalline structural phases of non-volatile phase-change materials (PCMs) provides a promising route towards tuneable nanophotonic devices. Here, we employ the next-generation PCM In3SbTe2 (IST) whose optical properties change from dielectric to metallic upon crystallization in the whole infrared spectral range. This distinguishes IST as a switchable infrared plasmonic PCM and enables a programmable nanophotonics material platform. We show how resonant metallic nanostructures can be directly written, modified and erased on and below the meta-atom level in an IST thin film by a pulsed switching laser, facilitating direct laser writing lithography without need for cumbersome multi-step nanofabrication. With this technology, we demonstrate large resonance shifts of nanoantennas of more than 4 µm, a tuneable mid-infrared absorber with nearly 90% absorptance as well as screening and nanoscale “soldering” of metallic nanoantennas. Our concepts can empower improved designs of programmable nanophotonic devices for telecommunications, (bio)sensing and infrared optics, e.g. programmable infrared detectors, emitters and reconfigurable holograms.

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Section: Resultsmentioning

confidence: 97%

In3SbTe2 as a programmable nanophotonics material platform for the infrared

et al. 2021

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“…[ 26,27 ] While the thermal parameters for the phase change need to be chosen carefully, a thorough thermodynamic analysis can allow for controlling and predicting the volumetric structural transition. [ 24,28 ]…”

Section: Figurementioning

confidence: 99%

“…To assess the potential of tip‐induced local switching of PCM thin films, we applied a self‐consistent multiphysics description to model the crystallization kinetics under the influence of a heated scanning probe. [ 28 ] While we formerly used this description for laser‐induced switching of Ge 2 Sb 2 Te 5 , [ 28 ] we extended the model to tip‐induced crystallization of GeTe (cf. Supporting Information).…”

Section: Figurementioning

confidence: 99%

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The Potential of Combining Thermal Scanning Probes and Phase‐Change Materials for Tunable Metasurfaces

Michel

Meyer

Essing

et al. 2020

Advanced Optical Materials

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ultra-thin equivalents, but may also introduce new functionalities (phase discontinuities, anomalous reflection, and refraction, etc.). [2,3] However, the shape of the wavefront is defined by the metasurface design, including material selection and geometry, and is fixed after fabrication. Active postfabrication control requires the tunability of the optical response of each metasurface element. [4,5] One common approach for active metasurfaces is to capitalize on the change of the material polarizabilityeither of the scatterer or its surroundings. This can be achieved, for example, by modulation of the charge density in doped semiconductors (e.g., GaAs) or graphene, [6] by changing the state of liquid crystals adjacent to metallic antennas, [7] or by including phase-transition (e.g., vanadium dioxide VO 2) [8-10] or phase-change [e.g., germanium antimony telluride (GeTe) x (Sb 2 Te 3) 1−x ] [11] materials in the metasurface. Mechanical tuning with stretchable substrates or actuators, [12] chemical reactions at the scatterers, [13] or enhanced optical nonlinearities [14] are other possible approaches for post-fabrication tunability. Phase-change materials (PCMs) are among the best-suited materials to provide tunability of metasurfaces due to the property contrast between their amorphous (A) and crystalline (C) phase. [15] In contrast to phase-transition materials (e.g., VO 2), PCMs feature non-volatile states and thus, no energy is needed to maintain the material properties. The structural change is accompanied with a refractive index change Δn = |n C − n A | Metasurfaces allow for the spatiotemporal variation of amplitude, phase, and polarization of optical wavefronts. Implementation of active tunability of metasurfaces promises compact flat optics capable of reconfigurable wavefront shaping. Phase-change materials (PCMs) are a prominent material class enabling reconfigurable metasurfaces due to their large refractive index change upon structural transition. However, commonly employed laser-induced switching of PCMs limits the achievable feature sizes and restricts device miniaturization. Thermal scanning-probe-induced local switching of the PCM germanium telluride is proposed to realize near-infrared metasurfaces with feature sizes far below what is achievable with diffraction-limited optical switching. The design is based on a planar multilayer and does not require fabrication of protruding resonators as commonly applied in the literature. Instead, it is numerically demonstrated that a broad-band tuning of perfect absorption can be realized by the localized tip-induced crystallization of the PCM. The spectral response of the metasurface is explained using resonance mode analysis and numerical simulations. To facilitate experimental realization, a theoretical description of the tip-induced crystallization employing multiphysics simulations is provided to demonstrate the great potential for fabricating compact reconfigurable metasurfaces. The concept can be applied not only for plasmonic sensing and spatial freq...

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“…substrate, PCM layer, superstrate) strongly influences the resulting local temperature during the non-stationary process. When the laser spot is heating a material boundary, both effects (intensity profile and change in thermal conductivity) lead to a spatially non-uniform phase transition 10 .…”

Section: Sample Fabrication and Layoutmentioning

confidence: 99%

Far-Infrared Near-Field Optical Imaging and Kelvin Probe Force Microscopy of Laser-Crystallized and -Amorphized Phase Change Material Ge3Sb2Te6

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Multiphysics simulations of adaptive metasurfaces at the meta-atom length scale

Cited by 16 publications

References 51 publications

In3SbTe2 as a programmable nanophotonics material platform for the infrared

In3SbTe2 as a programmable nanophotonics material platform for the infrared

The Potential of Combining Thermal Scanning Probes and Phase‐Change Materials for Tunable Metasurfaces

Far-Infrared Near-Field Optical Imaging and Kelvin Probe Force Microscopy of Laser-Crystallized and -Amorphized Phase Change Material Ge3Sb2Te6

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