All optically-controlled multifunctional VO2 memory device for terahertz waves

The highly hysteretic insulator-to-metal phase transition (IMT) of vanadium dioxide (VO2) enables an effective path to actively tuning terahertz (THz) wave, which holds great promise for the next generation optical memory devices. In the THz range, existed VO2-based memory device are driven by electric, which suffers some problems, such as slow write time at scale of several seconds, complicated circuit fabrication for electric conduction, and so on. Here, we propose an all optically-controlled THz wave memory device with inexpensive, straightforward and scalable fabrication of VO2. We demonstrate the reconfigurable THz-wave memory device with 1 bit and 2 bits programmed by two continuous lasers and its potential write time of tens of microseconds driven by ultrafast amplifier laser. This work paves the way for robust multifunctionality in optically-controlled terahertz switching, photonic memory, and ultrafast terahertz optics. And combining our memory device with spatial light modulator, its functionality can be further extended into spatial dimension, such as being a programmable and reconfigurable spatial THz wave modulator for the cutting-edge THz ghost imaging.