Highly-Oxidized Graphene Oxide for Achieving Low-Loss Hybrid Waveguide Gratings on SOI

Abstract

In this study we fabricated highly oxidized graphene oxides (GO) to reduce the optical bulk absorption, and to achieve a low-loss GO/silicon hybrid optical waveguide. The highly oxidized GO was fabricated using triple amount of oxidants and elongated oxidizing time via a modified Hummers’ method, together with post ozone treatment to effectively break down the C = C pi-conjugation network. The high oxidation degrees of GO were confirmed by a wide interlayer spacing (1.26 nm) in XRD patterns and a high fraction of oxygenated carbon (61.57%) observed in XPS spectra. Integrating a GO thin film on top of a silicon ring resonator revealed an extra optical loss of 1.2 dB/cm, while this value reduced to 0.8 dB/cm in a GO grating covered silicon strip waveguide. The resulting GO/silicon hybrid waveguide grating provided an extinction ratio of up to 35 dB at Bragg wavelength. We further demonstrated GO/silicon hybrid waveguide moiré gratings to provide dual stopbands with a controllable stopband interval from 2.5 to 20 nm. All results validate the promising optical properties of such GO material for low-loss heterogeneous integration on silicon-on-insulator.