Graphene-based modulator using GST-phase change material on semi-ellipsoid slot waveguide configuration

Abstract

A novel electro-absorption modulator (EAM) operating at the 1550 nm wavelength has been proposed, comprising graphene layers integrated with semi-ellipsoidal hafnium dioxide (HfO2) nanostructures embedded in a silicon dioxide (SiO2) substrate. This unique design offers several key advantages, including polarization-insensitive performance with a polarization sensitivity loss below 0.004 dB, an extended propagation length of 6800 μm, and a wide 3 dB bandwidth of 420.7 GHz. Furthermore, the mode power attenuation can be dynamically adjusted from 563.07 to 12669.15 dB/m by tuning the graphene's chemical potential, enabling precise control over the extinction ratio, which can be varied from 15 to 23.85 dB/μm. Through meticulous optimization of critical parameters, such as the number of graphene layers, dimensions, germanium-antimony-telluride (GST) thickness between graphene sheets, spacing between HfO2 semi-ellipsoids, and semi-ellipsoid dimensions, the electro-optic switching capabilities of this design have been significantly enhanced. This innovative graphene-hafnia EAM concept offers a low-cost, energy-efficient solution for optical modulation at the 1550 nm wavelength, a crucial requirement for telecommunication and optical computing applications. The reported optimization of the unique geometry and seamless integration of two-dimensional graphene with HfO2 nanostructures represent a major breakthrough in the development of narrowband EAMs, opening up new possibilities for next-generation photonic devices.