ИСТИНА

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.