All optically driven memory device for terahertz waves

We demonstrate an all optically driven memory device based on vanadium dioxide (VO2) for terahertz (THz) waves. By easily tuning the power of illuminating light, a VO2 memory device is coded in reconfigurable and multi-level states, taking advantage of its hysteretic metal-to-insulator phase transition (MIT). Further, writing with intense femtosecond pulses, the memory effects are performed by non-thermal photo-induced MIT, and resultant 2-bit coding with a write time of 22 mu s is demonstrated, yielding a dramatically improved write rate compared to existing thermally controlled VO2 memory device. The proposed all optically driven VO2-based memory device paves the way for actively manipulating THz waves within robust reconfigurable high-speed memory functionality. (C) 2019 Optical Society of America