Graphene Based Optical Interconnects

Abstract

Abstract By electrically tuning the Fermi level in graphene, it is possible to change its optical absorption in a broad range of wavelengths extending from the terahertz to the near-infrared (IR). This tunability enables the realization of graphene-based reconfigurable optoelectronic devices, e.g., ultrafast electro-absorption modulators, photodetectors, phase shifters, and so on. At IR frequencies, including the 1550-nm telecommunications band, both intraband and interband transitions become significant in graphene and can contribute to its optical absorption. In this chapter, we will discuss graphene, its optical properties, and the mechanisms behind the operation of graphene-based waveguide-integrated optoelectronic devices. Although our discussion will be mainly targeted toward modulator applications, most of the described principles can also be extended to other devices such as photodetectors. When considering that graphene is an atom-thick material, its optical response results truly remarkable. For instance, by placing graphene on top of a silicon ridge waveguide, it is possible to achieve a broadband electro-absorption modulation of 0.09\xa0dB/µm based on monolayer graphene and a modulation depth of 0.16\xa0dB/µm based on double-layer structures. Furthermore, we will also review emerging design approaches that can enable superior device performance, in particular we will discuss designer metamaterial approaches for the design of graphene-based optical modulators with reduced footprint.