Ultrafast Devices Based on Surface Plasmons on Bulk Metal and Graphene: Switches, Modulators, and Microscope Electron Sources

Optical modulation and switch are crucial in photonics technologies, and microscope electron sources are essential in imaging. However, it is an obstacle to integrating those devices with conventional techniques. Moreover, they cannot function in ultrafast communication and signal processing systems. The surface plasmon resonance phenomenon is of wide interest due to its abundant physics, such as the local field enhancement enabling strong light-matter interactions, breaking the diffraction limit to realize subwavelength structures, and going beyond the speed limit intrinsic to conventional semiconductor materials and devices. Here, by reviewing the various advantages of surface plasmons in different nanostructures or materials, we intend to propose the development trend and designed configuration of such ultrafast devices (usually induced by ultrafast laser) such as modulators, switches, and microscope electron sources. Based on the surface plasmons, ultrafast devices will tend to be more energy-efficient, low-energy consumption, and miniature. We also envision the development of surface plasmons with alternative materials or structures. This review will facilitate the development of ultrafast devices.