Analysis and Design of Forward Biased Silicon Photonics Phase Shifter Equalizer Circuits

A detailed investigation of driver concepts for forward biased silicon photonics phase shifters (FB-PSs), based on the free-carrier plasma dispersion effect (FCPD), is presented. A novel approach of operating FB-PSs in feedback loops of active equalizer (AE) circuits with matched RC filters is presented. It is investigated and compared to the known concepts of directly modulated and passively equalized FB-PS-based electro-optical transmitters (TXs), including a detailed physical phase shifter (PS) model. To allow for a direct comparison, the transfer functions of direct modulation (DM), passive equalizer (PE), and AE FB-PS TXs are derived and investigated regarding bandwidth and gain. Additionally, different biasing techniques for FB-PSs in electro-optical TXs are discussed. Furthermore, a PE and an AE TX are designed and compared to state-of-the-art reverse biased silicon phase shifter (RB-PS) based TX designs in electronic photonic integrated circuit (EPIC) technology. The PE and AE TXs require much less chip area than the RB-PS-based TXs. Moreover, it is shown, that in analytical analysis and in simulation, the newly introduced operation of FB-PSs in AE-based TX architectures allows for very high bandwidth and data communication at higher data rates than the PE TX and the RB-PS-based TXs.