A PAM-4 100 Gbps Single-Drive Strained SiGe Optical Lumped Mach-Zehnder Modulator for O-Band Application

We propose the carrier-depletion type strained SiGe optical lumped Mach-Zehnder modulators (MZMs) with L-shape PN junction (LSPN) with a highly CMOS-compatible fabrication method. The device performance is numerically investigated and optimized by technology computer-aided design (TCAD) simulation. The optimized SiGe LSPN MZ modulator exhibits a high modulation efficiency of 0.52 Vcm for
$V_{\pi }L$
with reverse bias voltages of 0V to −2V at 1310 nm wavelength, which is 3.5 times smaller than the conventional PN junction device thanks to strained SiGe. Furthermore, we carried out the large-signal simulation with 1-mW input power. As a result, we found that the SiGe LSPN MZ modulator can achieve 0.54 mW (−2.7 dBm) and 0.17 mW (−7.7 dBm) eye-openings for 50-Gbps NRZ-OOK and 100-Gbps PAM-4, respectively, taking advantage of single-drive configuration and optimizing input characteristics impedance. We expect this SiGe lumped MZ modulator can be one of the promising solutions for replacing a very long Si MZ modulator with traveling-wave electrodes.