Optical Transmitter Equalization With Tunable Mismatched Terminations in a Silicon Modulator

We demonstrate a 2.5 mm silicon photonics traveling-wave Mach-Zehnder modulator with on-chip tunable termination to study termination mismatching as a technique for optimizing modulator performance by leveraging the monolithic integration of electronic and photonic devices. Time domain reflectometry measurements demonstrate the tunability of the termination impedance with respect to the modulator transmission line Z
₀
. Electro-optic frequency response measurements show the bandwidth enhancement effect of the termination mismatch, whereby a 3 dB bandwidth above 40 GHz was achieved. Optical link time-domain measurements were performed to optimize the termination mismatch for maximum eye-diagram opening at 50 Gb/s. Our measurements demonstrate that active on-chip termination can be utilized to optimize the modulator performance and mitigate the risk incurred from fabrication variations which can result in a sub-optimal termination impedance.