Graphene-based plasmonic electro-absorption modulator on InP platform

Abstract

Graphene is an attractive material for photonic devices due to its many extraordinary properties including strong coupling with light, high-speed operation, and tunable optical guidance, which make it suitable for electro-optic modulators. Several types of graphene-based electro-optic modulators have been reported on several light-guiding platforms, including silicon-on-insulator (SOI) [1], lithium niobate [2], SiN [3], and polymers [4]. InP-platform gains several benefits concerning its rivals, mainly monolithic integration of passive and active devices (such as laser, semiconductor optical amplifier, photodetector, and modulator) [5]. Meanwhile, there are no reports on graphene-based devices on the InP platform. This article focuses on an electro-absorption (EA) modulator on a hybrid plasmonic InP-platform [6]at the 1.55m communication wavelength. In this article, we investigated an EA-modulator on a hybrid plasmonic waveguide with a three-layer of graphene as shown in Fig. 1. Fig. 2 demonstrates the electrical field distribution on the device lateral cross-section in two states of 0.4eV and 0.53 eV. By switching the chemical potential between two values of 0.4 eV and 0.53 eV, the optical absorption changes from the lowest value of 0.2 dB/m to the highest value of 6 dB/m for a 10 nm thick SiO2 layer. Meanwhile, the effect of SiO2 layer thickness on the effective refractive index (real and imaginary parts) was determined for various chemical potentials of graphene (see Fig. 3).