Terahertz AND-logic switching based on vanadium dioxide micro-ring resonators

The application of optical switches has attracted significant attention in recent years due to their potential in advanced communication systems and integrated photonics. Here, we propose a thermally tunable terahertz (THz) AND-logic switching device based on vanadium dioxide (VO₂) micro-ring resonators (MRRs) on a silicon platform. VO₂ exhibits an insulator-to-metal transition (IMT) characteristic at relatively low temperatures, and the conductivity can be increased by 4-5 orders of magnitude under external thermal pumps, with the a few picoseconds of rapid phase transition process, which allows for highly efficient modulation of THz waves. This transition shows significant advantages in terms of low-power operation and dynamic control over the THz response. Based on the IMT transition of VO₂, the device achieves precise control of THz waves, which enables reliable AND-logic operation. At low temperatures, when VO₂ is in the insulating phase, the hybrid VO₂ MRR exhibits logic “1”. Conversely, at high temperatures, when VO₂ transitions to the metallic phase, logic “0” is created. Simulation results demonstrate that when thermal stimulation is applied simultaneously to both micro-rings (A=1, B=1), the transmittance is greater than 0.8 at 1.5142THz, while for other input combinations, the transmittance close to 0. The modulation depth up to 84%. The simulated electric fields confirm that the AND logic operation function is mainly attributed to the VO₂ phase transition and the resonance effect of MRRs. The proposed VO₂-based structure demonstrates improved performance compared to conventional materials, including faster switching speeds, lower power consumption, and a higher degree of tunability across the THz spectrum. This work highlights the promise of VO₂ as a key material for next-generation tunable THz devices, offering a scalable solution for photonic and communication technologies.