Graphene Heaters for Tunable Mach–Zehnder Interferometers in Silicon Photonics at the C-Band Wavelength

Graphene micro heaters for thermally tunable photonic devices have great potential to improve the performance of Mach–Zehnder interferometers (MZI), because their low optical absorption allows placing them close to the photonic waveguides. In this work, we study MZI switches on the silicon-on-insulator (SOI) platform operated with graphene heaters at C-band wavelengths. We experimentally realize two different heater designs, vary the heater geometry of each design, investigate the switch performance, and compare it to state-of-the-art simulations. The best devices exhibit a Pπτ = 16 mW · 17 μs = 272 mW·μs and an extinction ratio of 28 dB. Our study demonstrates a precise and reliable fabrication process for graphene heaters with different geometry whose behavior can be well predicted with simulations.