Two to four THz decoding device with an encoding function based on the PCM and PIT effect

A terahertz metamaterial device based on plasma-induced transparency (PIT) and phase-change material (PCM), for the first time, to our knowledge, is proposed, which can achieve a 2-4 decoding function and a 2-bit encoding function. By changing the temperature of the VO₂ and adjusting the Fermi level of the graphene, a terahertz micro-nano device with polarization characteristics and the PIT effect is actively switched. When implementing the PIT effect, this device can achieve a 2-bit encoding function by separately controlling the Fermi level of the intermediate graphene layer, and the maximum modulation depth (MD) is 95%, the minimum extinction ratio (ER) is 10.42 dB, and the maximum insertion loss (IL) is 2.21 dB. When used as a metamaterial absorber (MMA), the device can achieve a 2-4 decoding function by changing the polarization angle of the incidence and the Fermi level of the top graphene layer, and the maximum modulation depth (MD) is 94.50%. The proposed switchable device has a simple structure and high integration degree, and is easy to tune. Therefore, this design will greatly promote the development of terahertz multifunctional devices.