Capacitively Coupled Silicon Modulator Fabricated on the Standard Silicon-on-Insulator Platform

Silicon-on-insulator (SOI) based silicon modulators are essential for modern optical communication links. Almost all these modulators are based on a rib waveguide structure. In this paper, we report our observation of a silicon modulator in a silicon strip waveguide. Such waveguide have a simpler structure, higher optical confinement, lower dispersion and can result in modulators with improved bandwidth compared to a rib waveguide. We demonstrated a novel strip waveguide-based Mach-Zehnder interferometer (MZI) silicon modulator fabricated in the Multi Project Wafer (MPW) run from a commercial foundry. Using a self-heterodyne measurement system we estimated a half-wave-voltage-length product (V <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$_{\pi }$</tex-math></inline-formula> L) of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\sim$</tex-math></inline-formula> 9.4 V.cm at 20 MHz modulation signal. The electro-optic (EO) measurement of the proposed modulator can generate the first order sidebands up to 68 GHz and almost a flat frequency response was observed.