A Bias Controller for Si Mach-Zehnder Modulator

We demonstrate a controller that can automatically determine the on-chip heater voltage required for the quadrature bias of the Si photonic Mach-Zehnder Modulator (MZM) and maintain this condition against fluctuations in temperature or the input optical power. The controller is implemented with an FPGA together with monitoring and driving circuits. Its operation is successfully demonstrated with a fabricated Si single-drive push-pull MZM.