Study of Zinc Diffusion Effect in High-Speed InP-Based Mach-Zehnder Modulators

We investigate the impact of Zinc diffusion on the modulation efficiency, absorption loss and 3-dB modulation bandwidth of high-speed InP-based Mach-Zehnder interferometer (MZI) modulators. By analyzing the electric-optical field distribution and capacitive-loaded traveling-wave electrode of MZI modulators with various waveguide structures under Zn diffusion effect, we show that InP-based MZI modulators will endure severe performance degradation when Zn diffuses into the active region during MOCVD epitaxy process. Quantitative analysis on modulation efficiency, absorption loss and 3-dB modulation bandwidth are demonstrated by commercial simulation software.