Creation of active optical metasurfaces on films of chalcogenide semiconductors with phase state change

Abstract

The development of meta-optics is due to human aspirations for the maximum miniaturization of optical elements, the design and control of light fluxes, as well as the improvement of visualization and image processing. Metasurfaces, i.e. arrays with subwavelength distances (smaller than the wavelength of light), and optically thin elements trigger new physical mechanism and phenomena that are very different from those observed in three-dimensional bulk materials. Thus, meta-devices perform complete control and management of the characteristics of the light flux (phase, amplitude, polarization) with the help of one flat layer. Compared to traditional bulky lenses, metasurface lenses have advantages such as flatness, light weight, and compatibility with semiconductor manufacturing technology. The use of active (reconfigurable) metasurfaces, the characteristics of which can be dynamically rearranged after manufacturing, makes it possible to significantly expand the capabilities of meta-optics. The paper presents the results of the analysis of the properties and technologies of creating optically active metasurfaces for optical image processing and transformation systems. Generalized methods of forming metasurfaces are described: self-organization, selective chemical etching, holographic and lithographic. To implement the work of active (reconfigured) metasurfaces based on materials with a change in phase state (amorphous/crystalline), heating technologies with electric current pulses of various amplitudes and durations and the action of direct optical radiation are used. The analysis of materials for the formation of optically active metasurfaces and devices based on them that simulate the front of a light wave and work on reflection and transmission is presented. Special attention is paid to the use of photosensitive chalcogenide semiconductors as metamaterials with a phase change. Examples of materials such as Ge2Sb2Te5 (GST) and AgxInSb2Te (AIST), which have been used for decades in optical data storage and electronic memory devices, are given. A series of novel compositions of optical phase change materials such as Ge2Sb2Se4Te (GSST), Sb2S3, Sb2Se3, Ge2Sb2Te3S2 and In3SbTe2 for optical and photonic applications are also proposed. Direct laser recording on photosensitive films of chalcogenide semiconductors with the use of technological equipment for laser recording of master disks is proposed as a promising method of forming arrays with submicron distances and realizing the work of active metasurfaces.