Analysis of a SiGe Mach–Zehnder modulator for 400G data communication

In this paper, the performance of a silicon (Si) Mach–Zehnder modulator (MZM) is enhanced by implanting germanium (Ge) on Si, forming a graded Si–Ge (SiGe) core. A process simulation study is done, and the effect of substrate temperature, implantation energy, and pre-amorphization on the Ge composition and developed in-plane stress is observed. The dependence of active dopant concentration and defect-cluster formation on the annealing conditions is discussed. A comparison of the process simulated SiGe phase shifter with a Si phase shifter shows 2.27× higher phase shift at −5 V for 1550 nm wavelength of operation. A dual-arm drive with quadrature operation is investigated for both SiGe and Si MZMs. A traveling-wave electrode is used to enhance the modulation bandwidth. The SiGe MZM achieves better performance in terms of modulation bandwidth, modulation speed, fiber transmission length, energy per bit, and dispersion tolerance compared to the Si MZM. The dual-arm driven SiGe MZM can achieve 62 Gbps error-free 2 km fiber transmission with energy per bit of 1.92 pJ/bit and 3 dB bandwidth of 62.8 GHz at −2.5 V bias using 3 V _pp on–off keying modulation.