High photoelectric conversion efficiency and fast relaxation time of FA0.4MA0.6PbI3 applied in ultrafast modulation of terahertz waves

Active control of terahertz (THz) waves is attracting tremendous attentions in terahertz communications and active photonic devices. Perovskite, due to its excellent photoelectric conversion performance and simple manufacturing process, has emerged as a promising candidate for optoelectronic applications. However, the exploration of perovskites in optically controlled THz modulators is still limited. In this work, the photoelectric properties and carrier dynamics of FA0.4MA0.6PbI3 perovskite films were investigated by optical pumped terahertz probe (OPTP) system. The ultrafast carrier dynamics reveal that FA0.4MA0.6PbI3 thin film exhibits rapid switching and relaxation time within picosecond level, suggesting that FA0.4MA0.6PbI3 is an ideal candidate for active THz devices with ultrafast response. Furthermore, as a proof of concept, a FA0.4MA0.6PbI3-based metadevice with integrating plasma-induced transparency (PIT) effect was fabricated to achieve ultrafast modulation of THz wave. The experimental results demonstrated that the switching time of FA0.4MA0.6PbI3-based THz modulator is near to 3.5 ps, and the threshold of optical pump is as low as 12.7 μJ cm−2. The simulation results attribute the mechanism of ultrafast THz modulation to photo-induced free carriers in the FA0.4MA0.6PbI3 layer, which progressively shorten the capacitive gap of PIT resonator. This study not only illuminates the potential of FA0.4MA0.6PbI3 in THz modulation, but also contributes to the field of ultrafast photonic devices.