Slow Light to Reduce the Energy Dissipation of Mach-Zehnder Modulators in Silicon Photonics

Integrated Mach-Zehnder (MZ) modulators are important components in silicon photonic devices that rely on a reverse-biased p-n junction to modulate the optical signal via a change of the waveguide refractive index [1]. Reducing their energy consumption is a crucial step towards the application of silicon photonics, especially in connection with the growing traffic volumes in data centers. In this work, we combine band-edge slow light structures consisting of silicon grating waveguides [2] with periodic (interlaced) p-n junctions [3,4] to maximize spatial matching between the optical field mode and the depletion region of the p-n junction. The two effects together will result in an improved modulation efficiency, leading to a strongly reduced energy dissipation per bit.