Integrated all-Si traveling-wave optical modulators and photodetectors operating beyond 40 GHz

Abstract. We present high-speed, traveling-wave (TW) Si Mach–Zehnder modulators and Si sub-bandgap photodetectors (SBPD) monolithically integrated on an Si-only photonics platform without incorporation of Ge epitaxial growth process. Through constructing a detailed equivalent circuit model on the components, we design the device structure and TW electrodes for operating the device with bandwidth beyond 40 GHz. The experimental results show the 3-dB bandwidths of the Si modulator and photodetectors are 35 and 44 GHz, respectively, generally agreeing well with our design. The measured photoresponsivity of the SBPD varies from 0.1  A  /  W to nearly 1  A  /  W, depending on the bias voltage. These two components potentially can be utilized for an integrated optical transceiver operating for 50  Gbit  /  s data transmission.