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2Telluride-based PCMs for controlling active THz devices
M. Konnikova1'2*, A. Tretiakov3, A. Shevchenko4, A. Mumlyakov4, M. Krasil'nikov4, A. Anikanov4, Yu, Kistenev3, I. Ozheredov12, A. Shkurinov1
1- Faculty of Physics, Lomonosov Moscow State University, 119991, Moscow, Russia 2- National Research Centre "Kurchatov Institute" (NRC "Kurchatov Institute") 3- Laboratory of Laser Molecular Imaging and Machine Learning, Tomsk State University, Tomsk, Russia 4- Institute of Nanotechnology of Microelectronics of the Russian Academy of Sciences, Moscow, Russia
Control of spectral and polarization characteristics of THz radiation is a key feature of next-generation wireless communication, sensing, and imaging devices in the THz band [1,2]. Phase change materials (PCMs) make a non-volatile phase transition from amorphous (insulating) to crystalline (conducting) state in nanosecond time intervals, changing their electrical and optical properties under thermal, electrical or optical influence. Since both states are characterized by strong differences in optical and electrical properties, these materials can be used for reconfigurable devices such as filters, amplitude, frequency, and polarization modulators [2]. The accurate retrieval of PCM film optical properties, such as its complex dielectric permittivity and conductivity, is key to creating reconfigurable devices for optical, infrared, and THz applications.
Here we propose a new approach to the study of PCM thin films, including simultaneous THz reflectance and transmittance measurements, which will minimize the uncertainty of the measured optical constants. Based on the calculated complex dielectric constant and conductivity of the films, we have designed and fabricated several tunable THz planar devices with a layer of tellurium compounds [2]. Laser irradiation parameters for optically induced phase transition of telluride-based PCMs films have been determined. The devices exhibit amplitude and frequency modulation of THz spectral characteristics at the phase transition of GeTe and GeTe2 films show in Fig. 1.
Fig. 1. The structures of tunable THz photonic devices based on GeTe and GeTe2 and their measured absorption spectra.
Thus, based on our measurements, we have designed unique THz active planar metastructures that change the frequency, amplitude and polarization characteristics of the THz field ultrafastly.
The research was carried out with the Tomsk State University Development Program (Priority-2030) in the theoretical part, within the state assignment of NRC "Kurchatov Institute" in the experimental part and by the Ministry of Science and Higher Education of the Russian Federation (Grant No. 075-15-2021-1353 and grant No. 075-15-2024-533) in the modeling part.
[1] A. Manda, Y. Cui, L. McRae, B. Gholipour, Reconfigurable chalcogenide phase change metamaterials: a material, device, and fabrication perspective, J. Phys. Photonics, vol. 3(2), 2021.
[2] M. Konnikova, M. Khomenko, et al, GeTe2 Phase Change Material for Terahertz Devices with Reconfigurable Functionalities Using
Optical Activation ACS Appl. Mater. Interfaces, vol. 15(7), 2023.
