A compact 120 GHz monolithic silicon-on-silica electro-optic modulator

A novel electro-optic modulator using the silicon-on-silica platform is proposed. The modulator utilizes a modified version of the gate-all-around switching mechanism which is well-known in MOSFET transistors. The waveguide silicon core is surrounded by oxide and metal to increase the effect of the applied voltage in charge depletion and accumulation and hence the optical phase shift. The modulator features a very high switching speed of 120GHz\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$120 \;{\text{GHz}}$$\end{document}, thanks to its very low capacitance, with a total insertion loss of 4.6dB\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$4.6 \;{\text{dB}}$$\end{document} and a phase-shifter length of 500μm\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$500 \;\upmu{\text{m}}$$\end{document}. The proposed modulator can therefore serve in high speed applications such as the backbone circuits of the new 5G telecommunications networks.