All-optical tuning of EIT-like dielectric metasurfaces by means of chalcogenide phase change materials

Abstract

Electromagnetically induced transparency (EIT) is a pump-induced narrowband transparency window within an absorption line of the probe beam spectrum in an atomic system. In this paper we propose a way to bring together the all-dielectric metamaterials to have EIT-like effects and to optically tune the response by hybridizing them with a layer of a phase change material. We propose a design of the metamaterial based on Si nanoresonators that can support an EIT-like resonant response. On the top of the resonators we consider a thin layer of a chalcogenide phase change material, which we will use to tune the optical response. Our choice is Ge₂Sb₂Te₅ (GST), since it has two stable phases at room temperature, namely amorphous and crystalline, between which it can be switched quickly, nonvolatively and reversibly, sustaining a large number of switching cycles. They differ in optical properties, while still having moderately low losses in telecom range. Since such dielectric resonators do not have non-radiative losses of metals around 1550nm, they can lead to a high-Q factor of the EIT-like response in this range. Firstly, we optimize the starting structure so that it gives an EIT-like response at 1550 nm when the GST layer is in the amorphous state. Our starting design uses glass as a substrate, but we also consider implementation in SOI technology. If we then switch the thin layer of GST to its crystalline phase, which has higher losses, the EIT-like response is red shifted, providing around 10:1 contrast at 1550nm. This reversible tuning can be done with an ns visible pulsed laser. We discuss the results of the simulation of the dielectric metasurface for different configurations and the tuning possibility.

Resonant Absorption in GaAs-Based Nanowires by Means of Photo-Acoustic Spectroscopy

“…PAS can therefore directly characterize the spectral position and the efficiency of the modes. For a specific application, one can optimize the geometric parameters, e.g., by using methods in [38] or [39]. One of the subjects of ongoing work is the use of the resonant modes for chiral near field formation.…”

Reversible switching of electromagnetically induced transparency in phase change metasurfaces

“…60 Particularly, a few works have numerically illustrated that the chalcogenide metasurfaces may lead to tunable EIT. [61][62][63] Following these theoretical predictions, the concept of tunable EIT was experimentally verified in a very recent work, which showed that a chalcogenide metasurface can be used to obtain a nonreversible switching of EIT via a thermal annealing system. 64 These previous works showed the promising potential of chalcogenide PCM in reconfigurable EIT metadevices in the optical region.…”

Analogue of Electromagnetically Induced Transparency in an S-Shaped All-Dielectric Metasurface

“…Recently, new strategies in view of the EIT or Fano resonances based on all-dielectric metasurfaces were introduced to restrain these losses, which have exhibited great possibility of producing high Q-factor resonances [16]- [32]. A common feature of the EIT-like all-dielectric metasurface demonstrated so far is dependent on multiple interacted structures within the unit cell, such as orthogonal silicon bars [25]- [27], silicon-based bar-ring resonator [28]- [30]. Generally in these resonator systems, one structure is designed to support the bright mode that can directly couple to the free space, the other one is served as a dark or trapped mode, which is less-accessible, or inaccessible from the incident optical field.…”