▎ 摘　　要

The new, to the best of our knowledge, phase modulator and optical switch based on graphene-coated fiber are proposed and studied. The fields of surface plasmon polaritons (SPP) modes are highly concentrated on the graphene so that very high effective indices (>400) can be achieved. By virtue of this feature, the dimensions of these devices can be as small as several nanometers in length. The minimum transmission losses for the phase modulator and optical switch are 0.54 dB and 0.18 dB, respectively. The maximum voltage adjustment range needed is only 0.3 V. The optical switch possesses a complete switch-off state and is adaptable to variation in phase difference and light intensity. The performance of these devices can be effectively tuned by the parameters, such as the graphene-coated lengths and the applied voltages. These devices may have important applications in fiber-based systems and other nanoscale optic and optoelectronic systems. (C) 2020 Optical Society of America