Design of graphene-on-germanium waveguide electro-optic modulators at the 2μm wavelength

The spectral region around 2 mu m wavelengths is of special significance for applications in optical communications, which is facing a capacity crunch at the telecommunication band. Development of CMOS-compatible on-chip photonic and optoelectronic devices operating in this spectral region is highly demanded but still at its infancy. In this paper, we present a design ;of graphene-on-germanium slot waveguides at the wavelength of 2 mu m. Due to the optical-field enhancement and poor mode confinement, light-matter interactions are enhanced in the graphene-on-germanium slot waveguide. Moreover, the influence of the refractive index contrast and the number of integrated graphene layers on the optical absorption enhancement of the slot waveguide is studied. Based on the graphene-on-slot waveguide configuration, energy-efficient and compact Mach-Zehnder interferometer and microring resonator phase modulators are designed. Our study paves the way for the development of on-chip electro-optic modulators at 2 mu m wavelengths. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement