A balanced ternary 2-9 decoder based on a terahertz metasurface and its sensing applications

With the development of terahertz communication technology, the demand for multi-valued logic functional devices has increased sharply. This is because, compared to binary logic devices, ternary logic devices can undertake more signal conversion with reduced input, reducing power consumption while also increasing information density. However, to the best of our knowledge, there are few works on terahertz metasurface multi-value decoders. Therefore, a balanced ternary 2-9 decoder of terahertz metamaterials based on graphene and strontium titanate (STO) was proposed for the first time. By controlling the voltage and temperature, 2-9 decoding functions can be achieved in the terahertz frequency band. The logic inputs can be -1, 0, and 1, belonging to multi-valued logic devices. Numerical validation shows that when the device achieves the 2-9 decoding function, the maximum modulation depth (MD) is 97.60%, the minimum extinction ratio (ER) is 1.05 dB, and the maximum insertion loss (IL) is 0.21 dB. At the same time, it has the characteristics of being insensitive to incident angle and polarization angle. In addition, the device can be used as a refractive index sensor and a temperature sensor, with sensitivities of 199.6 GHz RIU^-1 and 1.12 GHz K^-1, respectively. The device has relatively good performance in decoding and sensing functions. Therefore, this work provides new ideas for improving the decoding capability in terahertz single-chip and designing terahertz multi-value logic devices.